From phillor9 at gmail.com  Mon Nov  1 01:41:28 2021
From: phillor9 at gmail.com (Phil)
Date: Mon, 1 Nov 2021 15:41:28 +1000
Subject: [Tutor] Creating a two dimension set
In-Reply-To: <YX73qIoLdaN0KfMB@cskk.homeip.net>
References: <9e2be6f5-b825-5291-ff5b-103c74454f97@gmail.com>
 <YX73qIoLdaN0KfMB@cskk.homeip.net>
Message-ID: <74eb1922-ae3f-87e6-34f6-470b729239ba@gmail.com>


On 1/11/21 06:08, Cameron Simpson wrote:
> On 31Oct2021 15:56, Phil <phillor9 at gmail.com> wrote:
Thank you Cameron for answering my fool question. I've moved from our 
camping site with a frustrating Internet connection
>> As an example, if I wanted to create a two dimension list I would write:
>>
>> num_rows = 9
>> num_cols = 9
>>
>> self.solution = [[None] * num_cols for _ in range(num_rows)]
> Keeping in mind that this is a list of lists. Also, you're preallocating
> num_cols*nul_rows of storage. That can be wasteful if you're not filling
> much of it in.

This is a 9 x 9 grid that I use to solve Sudoku puzzles. It was working 
perfectly until I tried to make some improvements without saving the 
original file. A mistake that I haven't learned from.


> I do not fully understand your use case, partly because your second
> example is not sane Python.
>
> I'm also not sure you mean "set". Can you tell us in more detail what
> you're doing, maybe a very small example programme?

I had originally used 9 x 9 numpy arrays. I then decided to use a list 
of lists just as an exercise. The next version used sets because I 
wanted to experiment with set intersections. This worked well enough 
until I recently found a puzzle that my solver wouldn't solve correctly.

Say I have a 9 x 9 array, or a list of lists, and I want to remove a 
number from grid[0][7]. What simple method would I use? I've tried all 
sorts of complicated methods but I keep running into problems.

Removing an element from a set or a list is straight forward:

a = {1,2,3,4,5,6,7,8,9}
if 3 in a:
 ??? print('found')
 ??? a.remove(3)
print(a)

However, removing an element from a list of lists is problematic:

a = [['1','2','3'],['4','5','6']]

a[0][0] = '9'
a.remove('9')
print(a[0][0])

Traceback (most recent call last):
 ? File "/usr/lib/python3.9/idlelib/run.py", line 559, in runcode
 ??? exec(code, self.locals)
 ? File "/home/phil/Python/set_test.py", line 29, in <module>
 ??? a.remove('9')
ValueError: list.remove(x): x not in list

> Might I suggest a dict indexed by a 2-tuple of (row,col)?

Thank you for your detailed description of dictionaries, I'm not sure 
that a dictionary would be suitable for my case. Can a dictionary 
contain a set rather than a single number, it probably can? Like this:

grid = {}

grid[0,0] = {1,2,3,4,5,6,7,8,9}

What about removing a number, won't that fail as in a list of lists?

Each cell contains a set of candidate numbers (1 to 9). I run through a 
set (not to be confused with a mathematical set) of rules removing 
numbers from the candidates until the puzzle is solved.

I'm a bit frazzled from driving today, but I'll see if I can experiment 
with dictionaries later.

-- 

Regards,
Phil


From phillor9 at gmail.com  Mon Nov  1 03:18:33 2021
From: phillor9 at gmail.com (Phil)
Date: Mon, 1 Nov 2021 17:18:33 +1000
Subject: [Tutor] Creating a two dimension set
In-Reply-To: <YX73qIoLdaN0KfMB@cskk.homeip.net>
References: <9e2be6f5-b825-5291-ff5b-103c74454f97@gmail.com>
 <YX73qIoLdaN0KfMB@cskk.homeip.net>
Message-ID: <78e19bac-e5a9-4c47-2680-60869f13e7f6@gmail.com>


On 1/11/21 06:08, Cameron Simpson wrote:

Problem solved. Actually, the solution had nothing to do with my 
question. Too much looking and not enough seeing. The following works:

num_rows = 2
num_cols = 2

grid = [[str] * num_cols for _ in range(num_rows)] # I changed None to 
str but I don't thing it matters.

for row in range(2):
 ??? for col in range(2):
 ??????? grid[row][col] = set({'1', '2', '3', '4', '5', '6', '7', '8', '9'})

grid[0][0].remove('3')

print(grid[0][0])


I'm open to any improvements.

-- 

Regards,
Phil


From cs at cskk.id.au  Mon Nov  1 04:59:24 2021
From: cs at cskk.id.au (Cameron Simpson)
Date: Mon, 1 Nov 2021 19:59:24 +1100
Subject: [Tutor] Creating a two dimension set
In-Reply-To: <74eb1922-ae3f-87e6-34f6-470b729239ba@gmail.com>
References: <74eb1922-ae3f-87e6-34f6-470b729239ba@gmail.com>
Message-ID: <YX+sbM3hQvFIwMr+@cskk.homeip.net>

On 01Nov2021 15:41, Phil <phillor9 at gmail.com> wrote:
>
>On 1/11/21 06:08, Cameron Simpson wrote:
>>On 31Oct2021 15:56, Phil <phillor9 at gmail.com> wrote:
>Thank you Cameron for answering my fool question. I've moved from our 
>camping site with a frustrating Internet connection
>>>As an example, if I wanted to create a two dimension list I would write:
>>>
>>>num_rows = 9
>>>num_cols = 9
>>>
>>>self.solution = [[None] * num_cols for _ in range(num_rows)]
>>Keeping in mind that this is a list of lists. Also, you're preallocating
>>num_cols*nul_rows of storage. That can be wasteful if you're not filling
>>much of it in.
>
>This is a 9 x 9 grid that I use to solve Sudoku puzzles.

Tiny then. Don't worry about the space; do the simplest thing.

>It was working perfectly until I tried to make some improvements 
>without saving the original file. A mistake that I haven't learned 
>from.

Use revision control. It's just great!

>I had originally used 9 x 9 numpy arrays.

I guess that lets you do the grid directly. But numpy is kind of 
overkill for Sudoku in most regards.

Your followon post has a list of lists of sets, which covers things off 
nicely.

[...]
>>Might I suggest a dict indexed by a 2-tuple of (row,col)?
>
>Thank you for your detailed description of dictionaries, I'm not sure 
>that a dictionary would be suitable for my case. Can a dictionary 
>contain a set rather than a single number, it probably can? Like this:
>
>grid = {}
>grid[0,0] = {1,2,3,4,5,6,7,8,9}

Yes. List elements are Python references, just like any other Python 
variable. Referencing a set is no different to referencing a str or an 
int.

>What about removing a number, won't that fail as in a list of lists?

List of lists of sets. grid[0,0].remove(3)

>Each cell contains a set of candidate numbers (1 to 9). I run through 
>a set (not to be confused with a mathematical set) of rules removing 
>numbers from the candidates until the puzzle is solved.

Python sets are deliberately quite similar mathematical sets.

Cheers,
Cameron Simpson <cs at cskk.id.au>

From cs at cskk.id.au  Mon Nov  1 04:52:49 2021
From: cs at cskk.id.au (Cameron Simpson)
Date: Mon, 1 Nov 2021 19:52:49 +1100
Subject: [Tutor] Creating a two dimension set
In-Reply-To: <78e19bac-e5a9-4c47-2680-60869f13e7f6@gmail.com>
References: <78e19bac-e5a9-4c47-2680-60869f13e7f6@gmail.com>
Message-ID: <YX+q4cdeYl8rS5bG@cskk.homeip.net>

On 01Nov2021 17:18, Phil <phillor9 at gmail.com> wrote:
>Problem solved. Actually, the solution had nothing to do with my 
>question. Too much looking and not enough seeing. The following works:
>
>num_rows = 2
>num_cols = 2
>
>grid = [[str] * num_cols for _ in range(num_rows)] # I changed None to 
>str but I don't thing it matters.

Bare "str" isn't a good thing. Use None, it is the idiomatic Python 
value for "no value here" (there's a value, but it isn't in the expected 
range). Bare "str" means you've filled your lists with references to the 
str type. Kind of weird.

>for row in range(2):
>??? for col in range(2):
>??????? grid[row][col] = set({'1', '2', '3', '4', '5', '6', '7', '8', '9'})

You don't need to say "set({....})". The "{.....}" stuff is already a 
set. Except for "{}" which is an empty dict - for an empty set you need 
to say "set()".

I wouldn't use strings. If you're doing Sudoku don't you want to do 
arithmetic to check the sum? May as well make a set of ints:

    {1, 2, 3, 4, 5, 6, 7, 8, 9}

>grid[0][0].remove('3')

Yes. Of course, using ints would be grid[0][0][.remove(3). Adjust to 
suit.

If you wanted to simplify the setup you could fill the grid with empty 
sets instead and have it represent rejected values instead of potential 
values. Of course you'd have to turn some other logic upside down.

Cheers,
Cameron Simpson <cs at cskk.id.au>

From alan.gauld at yahoo.co.uk  Mon Nov  1 07:54:07 2021
From: alan.gauld at yahoo.co.uk (Alan Gauld)
Date: Mon, 1 Nov 2021 11:54:07 +0000
Subject: [Tutor] Creating a two dimension set
In-Reply-To: <74eb1922-ae3f-87e6-34f6-470b729239ba@gmail.com>
References: <9e2be6f5-b825-5291-ff5b-103c74454f97@gmail.com>
 <YX73qIoLdaN0KfMB@cskk.homeip.net>
 <74eb1922-ae3f-87e6-34f6-470b729239ba@gmail.com>
Message-ID: <slokh0$aja$1@ciao.gmane.io>

On 01/11/2021 05:41, Phil wrote:

> Say I have a 9 x 9 array, or a list of lists, and I want to remove a 
> number from grid[0][7]. What simple method would I use? I've tried all 
> sorts of complicated methods but I keep running into problems.

Normally using a 2D table i wouldn't use remove() I'd just
assign a new null value. However...

> However, removing an element from a list of lists is problematic:
> 
> a = [['1','2','3'],['4','5','6']]
> 
> a[0][0] = '9'
> a.remove('9')

a contains 2 lists. So there is no element '9'
You need to access the list that contains the 9:

a[0].remove('9')

But if you know the cell just reassign it directly

a[0][0] = ''

Its also safer since remove removes the first occurrence but if
you have multiple occurrences that might not be what you want.

> Thank you for your detailed description of dictionaries, I'm not sure 
> that a dictionary would be suitable for my case. Can a dictionary 
> contain a set rather than a single number, 

A dict can contain any python object no matter how complex.
Recall that python uses references, it does not store the
actual object in the dict but rather a reference.
So the reference can be to anything.


> grid[0,0] = {1,2,3,4,5,6,7,8,9}
> 
> What about removing a number, won't that fail as in a list of lists?

You call remove on the set not on the dict.

grid[0,0].remove(num)

grid[0,0] returns the set and remove() is then called on the set.

-- 
Alan G
Author of the Learn to Program web site
http://www.alan-g.me.uk/
http://www.amazon.com/author/alan_gauld
Follow my photo-blog on Flickr at:
http://www.flickr.com/photos/alangauldphotos



From wlfraed at ix.netcom.com  Mon Nov  1 11:30:16 2021
From: wlfraed at ix.netcom.com (Dennis Lee Bieber)
Date: Mon, 01 Nov 2021 11:30:16 -0400
Subject: [Tutor] Creating a two dimension set
References: <78e19bac-e5a9-4c47-2680-60869f13e7f6@gmail.com>
 <YX+q4cdeYl8rS5bG@cskk.homeip.net>
Message-ID: <rp10og51mqhfh6p1qtttq7c5on0hdcc9bq@4ax.com>

On Mon, 1 Nov 2021 19:52:49 +1100, Cameron Simpson <cs at cskk.id.au>
declaimed the following:

>I wouldn't use strings. If you're doing Sudoku don't you want to do 
>arithmetic to check the sum? May as well make a set of ints:
>
	No arithmetic done in Sudoku... You can replace the 1..9 with A..I, or
even emojis (if you can mentally keep track of such). The only thing one is
doing is eliminating candidates for a cell if that candidate was already
used on the row/column.



-- 
	Wulfraed                 Dennis Lee Bieber         AF6VN
	wlfraed at ix.netcom.com    http://wlfraed.microdiversity.freeddns.org/


From cs at cskk.id.au  Mon Nov  1 17:28:33 2021
From: cs at cskk.id.au (Cameron Simpson)
Date: Tue, 2 Nov 2021 08:28:33 +1100
Subject: [Tutor] Creating a two dimension set
In-Reply-To: <rp10og51mqhfh6p1qtttq7c5on0hdcc9bq@4ax.com>
References: <rp10og51mqhfh6p1qtttq7c5on0hdcc9bq@4ax.com>
Message-ID: <YYBcAfcX+f9QEkw+@cskk.homeip.net>

On 01Nov2021 11:30, Dennis Lee Bieber <wlfraed at ix.netcom.com> wrote:
>On Mon, 1 Nov 2021 19:52:49 +1100, Cameron Simpson <cs at cskk.id.au>
>declaimed the following:
>
>>I wouldn't use strings. If you're doing Sudoku don't you want to do
>>arithmetic to check the sum? May as well make a set of ints:
>>
>	No arithmetic done in Sudoku... You can replace the 1..9 with A..I, or
>even emojis (if you can mentally keep track of such). The only thing one is
>doing is eliminating candidates for a cell if that candidate was already
>used on the row/column.

Ah, my Sudoku inexperience is revealed. Thanks for the correction!

Cheers,
Cameron Simpson <cs at cskk.id.au>

From PyTutor at DancesWithMice.info  Mon Nov  1 18:23:43 2021
From: PyTutor at DancesWithMice.info (dn)
Date: Tue, 2 Nov 2021 11:23:43 +1300
Subject: [Tutor] Creating a two dimension set
In-Reply-To: <YYBcAfcX+f9QEkw+@cskk.homeip.net>
References: <rp10og51mqhfh6p1qtttq7c5on0hdcc9bq@4ax.com>
 <YYBcAfcX+f9QEkw+@cskk.homeip.net>
Message-ID: <770240d9-aa5f-6d27-2d5a-4fa5dcf9f8e3@DancesWithMice.info>



On 02/11/2021 10.28, Cameron Simpson wrote:
> On 01Nov2021 11:30, Dennis Lee Bieber <wlfraed at ix.netcom.com> wrote:
>> On Mon, 1 Nov 2021 19:52:49 +1100, Cameron Simpson <cs at cskk.id.au>
>> declaimed the following:
>>
>>> I wouldn't use strings. If you're doing Sudoku don't you want to do
>>> arithmetic to check the sum? May as well make a set of ints:
>>>
>> 	No arithmetic done in Sudoku... You can replace the 1..9 with A..I, or
>> even emojis (if you can mentally keep track of such). The only thing one is
>> doing is eliminating candidates for a cell if that candidate was already
>> used on the row/column.
> 
> Ah, my Sudoku inexperience is revealed. Thanks for the correction!

May be, may be not!

Rule: each column and each row must include the digits one to nine. Each
digit appearing once and only once.

Thus, re-stating the above slightly, the easiest way to verify a
Sudoku's completeness (assuming the use of integers - and remembering
sum() ) is to add the contents of each column and each row. If such a
total is not 45, there's something wrong!

NB I saw a code-competition where one ever-so keen fellow took this idea
and figured that the 9x9 tableau should also sum() to a unique number.
Was very proud of his 'improvement' until it was pointed-out that (if
that was the only check) complementary-errors would be 'missed'...


Sudoku, even the tic-tac-toe/noughts-and-crosses of my youth, is a very
good problem to stretch peoples' minds regarding concepts of
data-visualisation and thus data-structures. The most obvious approach
is probably to figure-out how to represent the tableau with a bunch of
digits arranged in rows and columns (just as on-paper).

However, some solutions make very clever use of indices/indexing. In
which case the 'actual data', can be a simple list() or dict().


That said, the OP's idea of comparing a column (say) as a list, with the
same list coerced to a set and then len()-s compared, is a good way to
detect duplicates!
-- 
Regards,
=dn

From manpritsinghece at gmail.com  Thu Nov  4 08:39:07 2021
From: manpritsinghece at gmail.com (Manprit Singh)
Date: Thu, 4 Nov 2021 18:09:07 +0530
Subject: [Tutor] Method overloading in Python
Message-ID: <CAO1OCwYzGvLC0KKjJ6gDNVeS9Jj9D2+o4z6n0KX8eynFBXTvuQ@mail.gmail.com>

Dear sir,

Although Method overloading  can't be truly achieved in Python , But a
similar effect can be made to happen - like if a method or __init__ () can
behave differently in case of different types of inputs.
I have written an example below to show it :

In this example i have  made a class Awards, My purpose of this class is to
get the name of award based on category
for category "A" or 1 award is "TV"
for category "B" or 2 award is "AC"
for category "C" or 3 award is "Fridge"

The program allows user to  give input of category either in string from or
in integer from, means the program must give result   as "TV" when the
category is either A or 1

class Awards:
    cat1 = {"A": "TV", "B": "AC", "C": "Fridge"}
    cat2 = {1: "TV", 2: "AC", 3: "Fridge"}

    def __init__(self, cat=None):
        if isinstance(cat, str):
            self.award = self.cat1[cat]
        elif isinstance(cat, int):
            self.award = self.cat2[cat]

    def showaward(self):
        return self.award

prize = Awards(1)
print(prize.showaward())    # prints "TV  which is right answer for
category 1

prize = Awards("A")           # prints "TV  which is right answer for
category "A
print(prize.showaward())

Here I have overloaded the __init__() , as it is behaving differently in
case of integer input and differently in case of string input. It will
assign "TV" to self.award if the  object creation is done either  with 1 or
"A" as argument  passed during class instantiation.  Is my thinking correct
?

My second question is if a class can have more than one class variable,
here I have put 2 class variables in the class cat1 and cat2 . Kindly
comment .

Kindly address any other shortcoming too .

Regards
Manprit Singh

From alan.gauld at yahoo.co.uk  Thu Nov  4 11:39:46 2021
From: alan.gauld at yahoo.co.uk (Alan Gauld)
Date: Thu, 4 Nov 2021 15:39:46 +0000
Subject: [Tutor] Method overloading in Python
In-Reply-To: <CAO1OCwYzGvLC0KKjJ6gDNVeS9Jj9D2+o4z6n0KX8eynFBXTvuQ@mail.gmail.com>
References: <CAO1OCwYzGvLC0KKjJ6gDNVeS9Jj9D2+o4z6n0KX8eynFBXTvuQ@mail.gmail.com>
Message-ID: <sm0us2$t4l$1@ciao.gmane.io>

On 04/11/2021 12:39, Manprit Singh wrote:
> Dear sir,
> 
> Although Method overloading  can't be truly achieved in Python , But a
> similar effect can be made to happen - like if a method or __init__ () can
> behave differently in case of different types of inputs.
> I have written an example below to show it :

While it is possible to do that, it's usually a bad code smell.

I'd question whether you might be better defining a few
classmethods as factory functions?

Alternatively, could you subclass the object with each
subclass taking different types of input?

The reason for these suggestions is that a class that needs multiple
constructors is usually loading from network or data store (in which
case use factory methods) or has some fundamentally different form of
internal data storage which should be split into two subclasses.

> In this example i have  made a class Awards, My purpose of this class is to
> get the name of award based on category
> for category "A" or 1 award is "TV"
> for category "B" or 2 award is "AC"
> for category "C" or 3 award is "Fridge"

So you could have a LetterAward and a StringAward?
(Or just convert the category to a string and use '1','2' etc
instead?

> The program allows user to  give input of category either in string from or
> in integer from, means the program must give result   as "TV" when the
> category is either A or 1
> 
> class Awards:
>     cat1 = {"A": "TV", "B": "AC", "C": "Fridge"}
>     cat2 = {1: "TV", 2: "AC", 3: "Fridge"}
> 
>     def __init__(self, cat=None):
>         if isinstance(cat, str):
>             self.award = self.cat1[cat]
>         elif isinstance(cat, int):
>             self.award = self.cat2[cat]
> 
>     def showaward(self):
>         return self.award

> Here I have overloaded the __init__() , as it is behaving differently in
> case of integer input and differently in case of string input. It will
> assign "TV" to self.award if the  object creation is done either  with 1 or
> "A" as argument  passed during class instantiation.  Is my thinking correct
> ?

It works, but has several problems with regard to maintainability,
not least being the potential of multiple if/elif options and having
to keep the inputs in step - the same 3 possible inputs. If you add
a new category you need to add a new input check. etc. It would
probably be better in this specific case to just   create the
awards class with a dict. But I know this is just a toy so lets
not get bogged down in example specific details.

But the point is that this is often a problem with this type of
overloaded initialiser. You wind up giving yourself maintenance headaches.

> My second question is if a class can have more than one class variable,

Sure, as many as you like.

-- 
Alan G
Author of the Learn to Program web site
http://www.alan-g.me.uk/
http://www.amazon.com/author/alan_gauld
Follow my photo-blog on Flickr at:
http://www.flickr.com/photos/alangauldphotos



From mats at wichmann.us  Thu Nov  4 12:04:21 2021
From: mats at wichmann.us (Mats Wichmann)
Date: Thu, 4 Nov 2021 10:04:21 -0600
Subject: [Tutor] Method overloading in Python
In-Reply-To: <CAO1OCwYzGvLC0KKjJ6gDNVeS9Jj9D2+o4z6n0KX8eynFBXTvuQ@mail.gmail.com>
References: <CAO1OCwYzGvLC0KKjJ6gDNVeS9Jj9D2+o4z6n0KX8eynFBXTvuQ@mail.gmail.com>
Message-ID: <c26bb9c1-12ef-fb61-a991-166e200b3708@wichmann.us>

On 11/4/21 06:39, Manprit Singh wrote:
> Dear sir,
> 
> Although Method overloading  can't be truly achieved in Python , But a
> similar effect can be made to happen - like if a method or __init__ () can
> behave differently in case of different types of inputs.
> I have written an example below to show it :
> 
> In this example i have  made a class Awards, My purpose of this class is to
> get the name of award based on category
> for category "A" or 1 award is "TV"
> for category "B" or 2 award is "AC"
> for category "C" or 3 award is "Fridge"
> 
> The program allows user to  give input of category either in string from or
> in integer from, means the program must give result   as "TV" when the
> category is either A or 1
> 
> class Awards:
>      cat1 = {"A": "TV", "B": "AC", "C": "Fridge"}
>      cat2 = {1: "TV", 2: "AC", 3: "Fridge"}
> 
>      def __init__(self, cat=None):
>          if isinstance(cat, str):
>              self.award = self.cat1[cat]
>          elif isinstance(cat, int):
>              self.award = self.cat2[cat]

Notice you have a default of None, meaning you're allowing the user to 
call with no arguments also, but you have no case for that.  On the 
other hand, this can have some advantages too, see below.

> 
>      def showaward(self):
>          return self.award
> 
> prize = Awards(1)
> print(prize.showaward())    # prints "TV  which is right answer for
> category 1
> 
> prize = Awards("A")           # prints "TV  which is right answer for
> category "A
> print(prize.showaward())
> 
> Here I have overloaded the __init__() , as it is behaving differently in
> case of integer input and differently in case of string input. It will
> assign "TV" to self.award if the  object creation is done either  with 1 or
> "A" as argument  passed during class instantiation.  Is my thinking correct
> ?

There are a couple of ways to achieve this "overloading".  One is how 
you've done it, which is to have the initializer handle different ways 
of calling.

Another way is to write a factory function that fronts the class 
definition, fiddling the arguments into some kind of common style, or 
passing some additional data like the already looked up data from the 
catalogs, and then your init method just becomes something like:

def __init__(self, award):
     self.award = award


  A another way is to provide an alternate initializer something like this:

     @classmethod
     def from_int(cls, cat):
         """ alternate initializer that takes an int argument """
         self = cls()
         self.award = self.cat2[cat]

That has the disadvantage that the "overloading" is user-visible, Which 
is also an advantage - depending on whether you think explicit is good 
or bad here.

Yet another approach is to use the functools module, which has 
singledispatch and singledispatchmethod calls - singldispatchmethod 
would be the one for this case.  I guess some people would consider that 
"advanced" Python so I won't go further into it here, but feel free to 
read up on it.

> My second question is if a class can have more than one class variable,
> here I have put 2 class variables in the class cat1 and cat2 . Kindly
> comment .

There''s no limit on number of class vaiables.

From kamenijames at yahoo.com  Fri Nov  5 11:29:42 2021
From: kamenijames at yahoo.com (James Kameni)
Date: Fri, 5 Nov 2021 15:29:42 +0000 (UTC)
Subject: [Tutor] Help for coding
References: <1892921862.504576.1636126182435.ref@mail.yahoo.com>
Message-ID: <1892921862.504576.1636126182435@mail.yahoo.com>

Hello,i am trying to solve the order batching problem using the tabu search in Jupyter Notebook and it doesn't work as i need.
Problem's definition:In manual order picking systems, order pickers walk or drive through a distribution warehouse (ref.file "Traversal.png") in order to collect items which are requested by (internal or external) customers. In order to perform these operations effciently, it is usually required that customer orders are combined into (more substantial) picking orders?(Batch)? of limited size. The Order Batching Problem deals with the question of how a given set of customer orders should be combined such that the total length of all tours is minimized which are necessary to collect all items.
data:
list of items and distances : "TD.txt"customers orders and quantities: "Auftrag.txt"
code: order batching problem.ipynb
Error:?I actually can't collect all items from orders requested by customers and put them into a batch. I only have a single solution.

can you give me tipps or some help?
ThanksJames
-------------- next part --------------
o	b	3
o	e	8
o	h	14
b	a	5
a	f	8
a	g	14
f	g	9
f	c	2
f	o	12
c	d	1
c	o	10
d	e	2
d	o	9
e	h	9
e	o	7
h	i	4
h	o	13
i	g	1
i	o	17
g	j	13
g	o	18
j	o	20
-------------- next part --------------
1	a	2		
1	b	3
1	c	1
2	d	5
2	e	2
2	a	7
3	f	2
3	g	6	
3	i	9		
4	h	1		
4	i	2
4	j	4

From PyTutor at DancesWithMice.info  Fri Nov  5 15:12:45 2021
From: PyTutor at DancesWithMice.info (dn)
Date: Sat, 6 Nov 2021 08:12:45 +1300
Subject: [Tutor] Help for coding
In-Reply-To: <1892921862.504576.1636126182435@mail.yahoo.com>
References: <1892921862.504576.1636126182435.ref@mail.yahoo.com>
 <1892921862.504576.1636126182435@mail.yahoo.com>
Message-ID: <d7214752-c9e5-0713-3277-16253de562e8@DancesWithMice.info>

On 06/11/2021 04.29, James Kameni via Tutor wrote:
> Hello,i am trying to solve the order batching problem using the tabu search in Jupyter Notebook and it doesn't work as i need.
> Problem's definition:In manual order picking systems, order pickers walk or drive through a distribution warehouse (ref.file "Traversal.png") in order to collect items which are requested by (internal or external) customers. In order to perform these operations effciently, it is usually required that customer orders are combined into (more substantial) picking orders?(Batch)? of limited size. The Order Batching Problem deals with the question of how a given set of customer orders should be combined such that the total length of all tours is minimized which are necessary to collect all items.
> data:
> list of items and distances : "TD.txt"customers orders and quantities: "Auftrag.txt"
> code: order batching problem.ipynb
> Error:?I actually can't collect all items from orders requested by customers and put them into a batch. I only have a single solution.
> 
> can you give me tipps or some help?
> ThanksJames


James, it is your homework, designed to help you prove your learning.
We'll be happy to help you with a Python problem.

What code have you written?
Please show it (or the pertinent routines) here.

Then we might be able to point-out where the code requires expansion or
correction...
-- 
Regards,
=dn

From alan.gauld at yahoo.co.uk  Sat Nov  6 07:05:03 2021
From: alan.gauld at yahoo.co.uk (Alan Gauld)
Date: Sat, 6 Nov 2021 11:05:03 +0000
Subject: [Tutor] Help for coding
In-Reply-To: <1892921862.504576.1636126182435@mail.yahoo.com>
References: <1892921862.504576.1636126182435.ref@mail.yahoo.com>
 <1892921862.504576.1636126182435@mail.yahoo.com>
Message-ID: <sm5nh0$n9c$1@ciao.gmane.io>

On 05/11/2021 15:29, James Kameni via Tutor wrote:
> Hello,i am trying to solve the order batching problem using the tabu search in Jupyter Notebook

Caveat: I don't know how to solve the order batching program,
I don't know what the tabu search is and I don;t use Jupyter
noteboook. However....

> list of items and distances : "TD.txt"customers orders and quantities: "Auftrag.txt"

You are lucky in that the list does not accept attachments - except
for pure text. So these two files made it through.

> code: order batching problem.ipynb

But this one didn't since the server doesn't recognise the
extension and even if it did wouldn't pass an executable file,

> can you give me tipps or some help?

Looking at your data files its not at all clear what they are!
However, I'm guessing its some kind of mesh or graph definition
and therefore the solution to your problem will involve
investigating mathematical graph theory.

To get more help here I think you'll need to send some code
and explain what the data files mean. Its best if you embed
those in the text of your mail rather that attaching files.

For example in TD.txt, what does

o	b	3
o	e	8
o	h	14
b	a	5
a	f	8
a	g	14
...
mean?

And in Auftrag.txt what does:
1	a	2		
1	b	3
1	c	1
2	d	5
2	e	2
...
mean.

And how are the two related?
It is not immediately obvious!
-- 
Alan G
Author of the Learn to Program web site
http://www.alan-g.me.uk/
http://www.amazon.com/author/alan_gauld
Follow my photo-blog on Flickr at:
http://www.flickr.com/photos/alangauldphotos



From manpritsinghece at gmail.com  Sat Nov  6 10:53:45 2021
From: manpritsinghece at gmail.com (Manprit Singh)
Date: Sat, 6 Nov 2021 20:23:45 +0530
Subject: [Tutor] Need help on regular expresions
Message-ID: <CAO1OCwZ=21VjoiDL_j6ASV01cuF92jaDNM8md1tZuXu7jKQ6=A@mail.gmail.com>

Dear Sir ,
Let's say i have to find if a string in question is of length 10, contains
at least four digits, one underscore and all other 5 characters must be
alphabets (upper or lowercase)

How would I do it with regular expressions ? Since this problem will be
very ugly with regular string methods,  that's why I would like to try it
with re's.

The below given example only checks if the string x is made up of 10
characters and contains numbers from 0-9 an underscore and alphabets a-z
and A-Z, but no count checks of numbers and alphabets and underscore . How
to do it?

import re
x = "aG4cD1_23fg"
if re.fullmatch(r'\w{10}', x):
    print("Match found")
else:
    print("No match")

Kindly guide

Regards
manprit Singh

From manpritsinghece at gmail.com  Sat Nov  6 11:01:17 2021
From: manpritsinghece at gmail.com (Manprit Singh)
Date: Sat, 6 Nov 2021 20:31:17 +0530
Subject: [Tutor] Need help on regular expresions
In-Reply-To: <CAO1OCwZ=21VjoiDL_j6ASV01cuF92jaDNM8md1tZuXu7jKQ6=A@mail.gmail.com>
References: <CAO1OCwZ=21VjoiDL_j6ASV01cuF92jaDNM8md1tZuXu7jKQ6=A@mail.gmail.com>
Message-ID: <CAO1OCwa-rchAK+g-UQ+9oz5Eyv3dgj9zq-ygdT=gw4Hh2FohVA@mail.gmail.com>

Dear sir ,

A little modification in my last mail,

Dear Sir ,
Let's say i have to find if a string in question is of length 10, contains
four digits, one underscore and all other 5 characters must be alphabets
(upper or lowercase)

How would I do it with regular expressions ? Since this problem will be
very ugly with regular string methods,  that's why I would like to try it
with re's.

The below given example only checks if the string x is made up of 10
characters and contains numbers from 0-9 an underscore and alphabets a-z
and A-Z, but no count checks of numbers and alphabets and underscore . How
to do it?

import re
x = "aG4cD1_23fg"
if re.fullmatch(r'\w{10}', x):
    print("Match found")
else:
    print("No match")

Kindly guide

Regards
manprit Sing

On Sat, Nov 6, 2021 at 8:23 PM Manprit Singh <manpritsinghece at gmail.com>
wrote:

> Dear Sir ,
> Let's say i have to find if a string in question is of length 10, contains
> at least four digits, one underscore and all other 5 characters must be
> alphabets (upper or lowercase)
>
> How would I do it with regular expressions ? Since this problem will be
> very ugly with regular string methods,  that's why I would like to try it
> with re's.
>
> The below given example only checks if the string x is made up of 10
> characters and contains numbers from 0-9 an underscore and alphabets a-z
> and A-Z, but no count checks of numbers and alphabets and underscore . How
> to do it?
>
> import re
> x = "aG4cD1_23fg"
> if re.fullmatch(r'\w{10}', x):
>     print("Match found")
> else:
>     print("No match")
>
> Kindly guide
>
> Regards
> manprit Singh
>
>
>

From Richard at Damon-Family.org  Sat Nov  6 11:29:04 2021
From: Richard at Damon-Family.org (Richard Damon)
Date: Sat, 6 Nov 2021 11:29:04 -0400
Subject: [Tutor] Need help on regular expresions
In-Reply-To: <CAO1OCwa-rchAK+g-UQ+9oz5Eyv3dgj9zq-ygdT=gw4Hh2FohVA@mail.gmail.com>
References: <CAO1OCwZ=21VjoiDL_j6ASV01cuF92jaDNM8md1tZuXu7jKQ6=A@mail.gmail.com>
 <CAO1OCwa-rchAK+g-UQ+9oz5Eyv3dgj9zq-ygdT=gw4Hh2FohVA@mail.gmail.com>
Message-ID: <61f87b19-62d5-28b7-398d-860064001dd0@Damon-Family.org>

My first thought is that this sounds very much like a case of having a 
hammer, so you want to treat something as a nail even if it isn't really 
one.

If this is a homework problem about thinking about regular expressions, 
that would be one thing, but if the problem really is identifying if the 
string has the right character membership, regular expressions are not 
the right tool.

Simplest would seem to be to iterate through the string, classify each 
character and keep a count, and then check those counts.

A regular expression can test a string for the presence of at least 3 
digits with a pattern something like (in english):

0 or more characters, 1 digit, 0 or more characters, 1 digit, 0 or more 
characters, 1 digit, 0 or more characters.

Using patterns like this you can check for each category requirement 
with a separate expression.

Getting a regular expression to check multiple parallel checks at the 
same times gets into much more advanced topics, and I would need to 
double check that python supports that level of syntax, but even if it 
does, unless there is some real reason it needs to be a single regular 
expression, it is much clearer to use multiple expressions for each 
requirement.


On 11/6/21 11:01 AM, Manprit Singh wrote:
> Dear sir ,
>
> A little modification in my last mail,
>
> Dear Sir ,
> Let's say i have to find if a string in question is of length 10, contains
> four digits, one underscore and all other 5 characters must be alphabets
> (upper or lowercase)
>
> How would I do it with regular expressions ? Since this problem will be
> very ugly with regular string methods,  that's why I would like to try it
> with re's.
>
> The below given example only checks if the string x is made up of 10
> characters and contains numbers from 0-9 an underscore and alphabets a-z
> and A-Z, but no count checks of numbers and alphabets and underscore . How
> to do it?
>
> import re
> x = "aG4cD1_23fg"
> if re.fullmatch(r'\w{10}', x):
>      print("Match found")
> else:
>      print("No match")
>
> Kindly guide
>
> Regards
> manprit Sing
>
> On Sat, Nov 6, 2021 at 8:23 PM Manprit Singh <manpritsinghece at gmail.com>
> wrote:
>
>> Dear Sir ,
>> Let's say i have to find if a string in question is of length 10, contains
>> at least four digits, one underscore and all other 5 characters must be
>> alphabets (upper or lowercase)
>>
>> How would I do it with regular expressions ? Since this problem will be
>> very ugly with regular string methods,  that's why I would like to try it
>> with re's.
>>
>> The below given example only checks if the string x is made up of 10
>> characters and contains numbers from 0-9 an underscore and alphabets a-z
>> and A-Z, but no count checks of numbers and alphabets and underscore . How
>> to do it?
>>
>> import re
>> x = "aG4cD1_23fg"
>> if re.fullmatch(r'\w{10}', x):
>>      print("Match found")
>> else:
>>      print("No match")
>>
>> Kindly guide
>>
>> Regards
>> manprit Singh
>>
>>
>>
> _______________________________________________
> Tutor maillist  -  Tutor at python.org
> To unsubscribe or change subscription options:
> https://mail.python.org/mailman/listinfo/tutor


-- 
Richard Damon


From wlfraed at ix.netcom.com  Sat Nov  6 12:09:54 2021
From: wlfraed at ix.netcom.com (Dennis Lee Bieber)
Date: Sat, 06 Nov 2021 12:09:54 -0400
Subject: [Tutor] Need help on regular expresions
References: <CAO1OCwZ=21VjoiDL_j6ASV01cuF92jaDNM8md1tZuXu7jKQ6=A@mail.gmail.com>
Message-ID: <bt7doglanl0tpmpcdnf7m4up80gf4fleru@4ax.com>

On Sat, 6 Nov 2021 20:23:45 +0530, Manprit Singh
<manpritsinghece at gmail.com> declaimed the following:

>
>How would I do it with regular expressions ? Since this problem will be
>very ugly with regular string methods,  that's why I would like to try it
>with re's.
>
	I wouldn't...

	To my understanding, regex do not do COUNTING, so your first criteria
is not possible. You CAN specify that a regex matches, say, four
CONSECUTIVE digits (using \d{4] ), but you can't say "match four SCATTERED
digits".

https://docs.microsoft.com/en-us/dotnet/standard/base-types/quantifiers-in-regular-expressions

	It also doesn't seem that difficult using string methods...

-=-=-=-

TESTTEXT = "aG4cD1_23fg"
TESTTEXT2 = "Ag4C1_23Fg"
TESTTEXT3 = "Ag4Cd123Fg"

def checkText(text, lenLimit, reqDigits, reqUnderscore, reqAlpha):
    if lenLimit != sum([reqDigits, reqUnderscore, reqAlpha]):
        raise ValueError("Sum of required characters does not match length
limit")
    for ch in text:
        if ch == "_": reqUnderscore -= 1
        if ch.isdecimal(): reqDigits -= 1   #or maybe .isdigit()
        if ch.isalpha(): reqAlpha -= 1      #or maybe .isascii()

    return (len(text) == lenLimit
            and reqDigits == 0
            and reqAlpha == 0
            and reqUnderscore == 0)

if __name__ == "__main__":
    print("%s\t%s" % (TESTTEXT, checkText(TESTTEXT, 10, 4, 1, 5)))
    print("%s\t%s" % (TESTTEXT2, checkText(TESTTEXT2, 10, 4, 1, 5)))
    print("%s\t%s" % (TESTTEXT3, checkText(TESTTEXT3, 10, 4, 1, 5)))
    print("%s\t%s" % (TESTTEXT3, checkText(TESTTEXT3, 10, 4, 2, 5)))

-=-=-=-
aG4cD1_23fg	False
Ag4C1_23Fg	True
Ag4Cd123Fg	False
Traceback (most recent call last):
  File
"C:\Python38\Lib\site-packages\pythonwin\pywin\framework\scriptutils.py",
line 326, in RunScript
    exec(codeObject, __main__.__dict__)
  File "C:\Users\Wulfraed\Documents\_Hg-Repositories\Python
Progs\CheckText.py", line 23, in <module>
    print("%s\t%s" % (TESTTEXT3, checkText(TESTTEXT3, 10, 4, 2, 5)))
  File "C:\Users\Wulfraed\Documents\_Hg-Repositories\Python
Progs\CheckText.py", line 8, in checkText
    raise ValueError("Sum of required characters does not match length
limit")
ValueError: Sum of required characters does not match length limit 
-=-=-=-


-- 
	Wulfraed                 Dennis Lee Bieber         AF6VN
	wlfraed at ix.netcom.com    http://wlfraed.microdiversity.freeddns.org/


From manpritsinghece at gmail.com  Sat Nov  6 12:11:24 2021
From: manpritsinghece at gmail.com (Manprit Singh)
Date: Sat, 6 Nov 2021 21:41:24 +0530
Subject: [Tutor] Need help on regular expresions
In-Reply-To: <61f87b19-62d5-28b7-398d-860064001dd0@Damon-Family.org>
References: <CAO1OCwZ=21VjoiDL_j6ASV01cuF92jaDNM8md1tZuXu7jKQ6=A@mail.gmail.com>
 <CAO1OCwa-rchAK+g-UQ+9oz5Eyv3dgj9zq-ygdT=gw4Hh2FohVA@mail.gmail.com>
 <61f87b19-62d5-28b7-398d-860064001dd0@Damon-Family.org>
Message-ID: <CAO1OCwZLZQq8dyhsAcWYTqwTSWjLe2B5NAivTLw4AtQMW9vNcw@mail.gmail.com>

Dear Richard,

I know this can be done with string methods, I was just willing to know if
this can be done using re in an easy way or not .

Thanks for your mail.

Regards
Manprit Singh


On Sat, Nov 6, 2021 at 9:00 PM Richard Damon <Richard at damon-family.org>
wrote:

> My first thought is that this sounds very much like a case of having a
> hammer, so you want to treat something as a nail even if it isn't really
> one.
>
> If this is a homework problem about thinking about regular expressions,
> that would be one thing, but if the problem really is identifying if the
> string has the right character membership, regular expressions are not
> the right tool.
>
> Simplest would seem to be to iterate through the string, classify each
> character and keep a count, and then check those counts.
>
> A regular expression can test a string for the presence of at least 3
> digits with a pattern something like (in english):
>
> 0 or more characters, 1 digit, 0 or more characters, 1 digit, 0 or more
> characters, 1 digit, 0 or more characters.
>
> Using patterns like this you can check for each category requirement
> with a separate expression.
>
> Getting a regular expression to check multiple parallel checks at the
> same times gets into much more advanced topics, and I would need to
> double check that python supports that level of syntax, but even if it
> does, unless there is some real reason it needs to be a single regular
> expression, it is much clearer to use multiple expressions for each
> requirement.
>
>
> On 11/6/21 11:01 AM, Manprit Singh wrote:
> > Dear sir ,
> >
> > A little modification in my last mail,
> >
> > Dear Sir ,
> > Let's say i have to find if a string in question is of length 10,
> contains
> > four digits, one underscore and all other 5 characters must be alphabets
> > (upper or lowercase)
> >
> > How would I do it with regular expressions ? Since this problem will be
> > very ugly with regular string methods,  that's why I would like to try it
> > with re's.
> >
> > The below given example only checks if the string x is made up of 10
> > characters and contains numbers from 0-9 an underscore and alphabets a-z
> > and A-Z, but no count checks of numbers and alphabets and underscore .
> How
> > to do it?
> >
> > import re
> > x = "aG4cD1_23fg"
> > if re.fullmatch(r'\w{10}', x):
> >      print("Match found")
> > else:
> >      print("No match")
> >
> > Kindly guide
> >
> > Regards
> > manprit Sing
> >
> > On Sat, Nov 6, 2021 at 8:23 PM Manprit Singh <manpritsinghece at gmail.com>
> > wrote:
> >
> >> Dear Sir ,
> >> Let's say i have to find if a string in question is of length 10,
> contains
> >> at least four digits, one underscore and all other 5 characters must be
> >> alphabets (upper or lowercase)
> >>
> >> How would I do it with regular expressions ? Since this problem will be
> >> very ugly with regular string methods,  that's why I would like to try
> it
> >> with re's.
> >>
> >> The below given example only checks if the string x is made up of 10
> >> characters and contains numbers from 0-9 an underscore and alphabets a-z
> >> and A-Z, but no count checks of numbers and alphabets and underscore .
> How
> >> to do it?
> >>
> >> import re
> >> x = "aG4cD1_23fg"
> >> if re.fullmatch(r'\w{10}', x):
> >>      print("Match found")
> >> else:
> >>      print("No match")
> >>
> >> Kindly guide
> >>
> >> Regards
> >> manprit Singh
> >>
> >>
> >>
> > _______________________________________________
> > Tutor maillist  -  Tutor at python.org
> > To unsubscribe or change subscription options:
> > https://mail.python.org/mailman/listinfo/tutor
>
>
> --
> Richard Damon
>
> _______________________________________________
> Tutor maillist  -  Tutor at python.org
> To unsubscribe or change subscription options:
> https://mail.python.org/mailman/listinfo/tutor
>

From alan.gauld at yahoo.co.uk  Sat Nov  6 18:54:11 2021
From: alan.gauld at yahoo.co.uk (Alan Gauld)
Date: Sat, 6 Nov 2021 22:54:11 +0000
Subject: [Tutor] Need help on regular expresions
In-Reply-To: <CAO1OCwa-rchAK+g-UQ+9oz5Eyv3dgj9zq-ygdT=gw4Hh2FohVA@mail.gmail.com>
References: <CAO1OCwa-rchAK+g-UQ+9oz5Eyv3dgj9zq-ygdT=gw4Hh2FohVA@mail.gmail.com>
Message-ID: <23A2C51A-7127-4ABF-BE50-832D85BB63FF@yahoo.co.uk>


> Let's say i have to find if a string in question is of length 10, contains
> four digits, one underscore and all other 5 characters must be alphabets
> (upper or lowercase)
> 

A slightly different approach:

s = "1a2b3c4dE_"

s2 = ''.join(sorted(s.lower()))
print(s2)

num,ltr = s2.split('_')
print(num,ltr)

if len(s) == 10 and len(num) == 4 and len(ltr) == 5:
	print("Success!")
	
> How would I do it with regular expressions ? Since this problem will be
> very ugly with regular string methods,

Reyes looks for patterns but you do not have a pattern, just a set 
of count based rules. Regex  is not a good solution in this case. 
Regex is great for complex  patterns but when you try to force 
it into other roles it doesn?t work so well.

Alan G.
(Sent from my iPad coz my PC is offline?)



From kaushalshriyan at gmail.com  Sat Nov  6 05:41:45 2021
From: kaushalshriyan at gmail.com (Kaushal Shriyan)
Date: Sat, 6 Nov 2021 15:11:45 +0530
Subject: [Tutor] ModuleNotFoundError: No module named 'mysql' in Python
 3.10.0 (default, Nov 6 2021,
 14:56:25) [GCC 4.8.5 20150623 (Red Hat 4.8.5-44)] on linux
Message-ID: <CAD7Ssm_kPD7R3b8JVm8MUUnkMqtp=J5J3TZDzTEC9Fa13wk8hQ@mail.gmail.com>

Hi,

I have downloaded Python 3.10.0 on CentOS Linux release 7.9.2009 (Core). I
have the below openssl and mariadb package installed on CentOS 7.9

# rpm -qa | grep openssl
openssl-libs-1.0.2k-22.el7_9.x86_64
openssl-devel-1.0.2k-22.el7_9.x86_64
openssl-1.0.2k-22.el7_9.x86_64

#rpm -qa | grep mariadb
mariadb-libs-5.5.68-1.el7.x86_64
mariadb-5.5.68-1.el7.x86_64
mariadb-server-5.5.68-1.el7.x86_64
mariadb-devel-5.5.68-1.el7.x86_64
#
#mysql -p
Enter password:
Welcome to the MariaDB monitor.  Commands end with ; or \g.
Your MariaDB connection id is 2
Server version: 5.5.68-MariaDB MariaDB Server

Copyright (c) 2000, 2018, Oracle, MariaDB Corporation Ab and others.

Type 'help;' or '\h' for help. Type '\c' to clear the current input
statement.

MariaDB [(none)]> Bye
#

#wget https://www.python.org/ftp/python/3.10.0/Python-3.10.0.tgz
#tar xzf Python-3.10.0.tgz
#cd Python-3.10.0
#./configure --enable-optimizations
#make altinstall

# python3.10
Python 3.10.0 (default, Nov  6 2021, 14:56:25) [GCC 4.8.5 20150623 (Red Hat
4.8.5-44)] on linux
Type "help", "copyright", "credits" or "license" for more information.
>>> import mysql.connector
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
ModuleNotFoundError: No module named 'mysql'
>>>

#cat demo_mysql_test.py
import mysql.connector
# python3.10 demo_mysql_test.py
Traceback (most recent call last):
  File "/root/demo_mysql_test.py", line 1, in <module>
    import mysql.connector
ModuleNotFoundError: No module named 'mysql'
#

# pip3.10 install mysql-connector-python
WARNING: pip is configured with locations that require TLS/SSL, however the
ssl module in Python is not available.
WARNING: Retrying (Retry(total=4, connect=None, read=None, redirect=None,
status=None)) after connection broken by 'SSLError("Can't connect to HTTPS
URL because the SSL module is not available.")':
/simple/mysql-connector-python/
WARNING: Retrying (Retry(total=3, connect=None, read=None, redirect=None,
status=None)) after connection broken by 'SSLError("Can't connect to HTTPS
URL because the SSL module is not available.")':
/simple/mysql-connector-python/
WARNING: Retrying (Retry(total=2, connect=None, read=None, redirect=None,
status=None)) after connection broken by 'SSLError("Can't connect to HTTPS
URL because the SSL module is not available.")':
/simple/mysql-connector-python/
WARNING: Retrying (Retry(total=1, connect=None, read=None, redirect=None,
status=None)) after connection broken by 'SSLError("Can't connect to HTTPS
URL because the SSL module is not available.")':
/simple/mysql-connector-python/
WARNING: Retrying (Retry(total=0, connect=None, read=None, redirect=None,
status=None)) after connection broken by 'SSLError("Can't connect to HTTPS
URL because the SSL module is not available.")':
/simple/mysql-connector-python/
Could not fetch URL https://pypi.org/simple/mysql-connector-python/: There
was a problem confirming the ssl certificate: HTTPSConnectionPool(host='
pypi.org', port=443): Max retries exceeded with url:
/simple/mysql-connector-python/ (Caused by SSLError("Can't connect to HTTPS
URL because the SSL module is not available.")) - skipping
ERROR: Could not find a version that satisfies the requirement
mysql-connector-python (from versions: none)
ERROR: No matching distribution found for mysql-connector-python
WARNING: You are using pip version 21.2.3; however, version 21.3.1 is
available.
You should consider upgrading via the '/usr/local/bin/python3.10 -m pip
install --upgrade pip' command.

Please guide me and let me know if I am missing anything. Thanks in advance
and I look forward to hearing from you.

Best Regards,

Kaushal

From alan.gauld at yahoo.co.uk  Sat Nov  6 21:08:48 2021
From: alan.gauld at yahoo.co.uk (Alan Gauld)
Date: Sun, 7 Nov 2021 01:08:48 +0000
Subject: [Tutor] Need help on regular expresions
In-Reply-To: <CAO1OCwZLZQq8dyhsAcWYTqwTSWjLe2B5NAivTLw4AtQMW9vNcw@mail.gmail.com>
References: <CAO1OCwZ=21VjoiDL_j6ASV01cuF92jaDNM8md1tZuXu7jKQ6=A@mail.gmail.com>
 <CAO1OCwa-rchAK+g-UQ+9oz5Eyv3dgj9zq-ygdT=gw4Hh2FohVA@mail.gmail.com>
 <61f87b19-62d5-28b7-398d-860064001dd0@Damon-Family.org>
 <CAO1OCwZLZQq8dyhsAcWYTqwTSWjLe2B5NAivTLw4AtQMW9vNcw@mail.gmail.com>
Message-ID: <sm78v0$11oh$1@ciao.gmane.io>

On 06/11/2021 16:11, Manprit Singh wrote:
> Dear Richard,
> 
> I know this can be done with string methods, I was just willing to know if
> this can be done using re in an easy way or not .

For some definition of easy...

if ((len(s) == 10) and
    (len(re.findall(r'\d',s)) == 4) and
    (len(re.findall(r'[a-zA-Z]',s)) == 5) and
     '_' in s):
	print("Success")
else: print("Fail!")

But I'm not sure that's any easier than using the plain string methods.

-- 
Alan G
Author of the Learn to Program web site
http://www.alan-g.me.uk/
http://www.amazon.com/author/alan_gauld
Follow my photo-blog on Flickr at:
http://www.flickr.com/photos/alangauldphotos



From ewenjamet73 at gmail.com  Sat Nov  6 20:47:35 2021
From: ewenjamet73 at gmail.com (Ewen Jamet)
Date: Sat, 6 Nov 2021 20:47:35 -0400
Subject: [Tutor] Help
Message-ID: <CABtPu_xpM3NvKPVrfdrkxgMOcxRVdJ-4ipAUNsz-fv3ww8PyKQ@mail.gmail.com>

Hello,
Does someone can help me i face an issur with plotting on cartopy and it is
really important that I achieve that tonight.. i would be really greatful
Best
Ewen Jamet

From alan.gauld at yahoo.co.uk  Sat Nov  6 21:17:49 2021
From: alan.gauld at yahoo.co.uk (Alan Gauld)
Date: Sun, 7 Nov 2021 01:17:49 +0000
Subject: [Tutor] Help
In-Reply-To: <CABtPu_xpM3NvKPVrfdrkxgMOcxRVdJ-4ipAUNsz-fv3ww8PyKQ@mail.gmail.com>
References: <CABtPu_xpM3NvKPVrfdrkxgMOcxRVdJ-4ipAUNsz-fv3ww8PyKQ@mail.gmail.com>
Message-ID: <sm79ft$5qn$1@ciao.gmane.io>

On 07/11/2021 00:47, Ewen Jamet wrote:
> Hello,
> Does someone can help me i face an issur with plotting on cartopy and it is
> really important that I achieve that tonight.. i would be really greatful

You are posting to an email list (email can take up to 24 hours to
arrive) based all around the world - so where are you and what time is
"night" where you live? And you are asking about "plotting on cartopy"
which are not standard Python modules (this list is specifically for
the core language and standard library). Finally, you ask for help on
"an issue" but give no clue to what the issue is, nor do you show us any
code, data, error messages etc.

In short, you are not helping yourself to get answers, far less by
"tonight" whenever that is.

Should you find yourself in a similar position in the future think
carefully about all of the above points before sending out a request
for help and you may have more success.

-- 
Alan G
Author of the Learn to Program web site
http://www.alan-g.me.uk/
http://www.amazon.com/author/alan_gauld
Follow my photo-blog on Flickr at:
http://www.flickr.com/photos/alangauldphotos



From ewenjamet73 at gmail.com  Sat Nov  6 22:46:57 2021
From: ewenjamet73 at gmail.com (Ewen Jamet)
Date: Sat, 6 Nov 2021 22:46:57 -0400
Subject: [Tutor] Fwd:  Help
In-Reply-To: <CABtPu_yR=rY2DWAb8njra9Kp62+L1JHasUp3yHaryoG=oeiewA@mail.gmail.com>
References: <CABtPu_xpM3NvKPVrfdrkxgMOcxRVdJ-4ipAUNsz-fv3ww8PyKQ@mail.gmail.com>
 <771BC361-7C05-4EBD-BE68-974A9E9926B7@me.com>
 <CABtPu_yR=rY2DWAb8njra9Kp62+L1JHasUp3yHaryoG=oeiewA@mail.gmail.com>
Message-ID: <CABtPu_xpPdfYU_EkvAkC3P=ChD0Gd=Fegb7CkG3d+yWB1Ua1dQ@mail.gmail.com>

---------- Forwarded message ---------
De : Ewen Jamet <ewenjamet73 at gmail.com>
Date: sam. 6 nov. 2021 ? 21:35
Subject: Re: [Tutor] Help
To: Brett Leach <brettlea at me.com>


Hello!!!
Thank you very much for answering, i am in trouble if i don't fix this..
Well the problem is: I use cartopy to plot geophysics data, and cartopy
feature (coastline etc, the map basicaly) are disappearing when I plot the
data, as you can see on the screenshot sent, I can not understand why..
Thank you if you take time to look at this, I would be very grateful.
Best,
Ewen Jamet


Python 3.8.10

DISTRIB_ID=Ubuntu
DISTRIB_RELEASE=20.04
DISTRIB_CODENAME=focal
DISTRIB_DESCRIPTION="Ubuntu 20.04.3 LTS"
NAME="Ubuntu"
VERSION="20.04.3 LTS (Focal Fossa)"
ID=ubuntu
ID_LIKE=debian
PRETTY_NAME="Ubuntu 20.04.3 LTS"
VERSION_ID="20.04"
HOME_URL="https://www.ubuntu.com/"
SUPPORT_URL="https://help.ubuntu.com/"
BUG_REPORT_URL="https://bugs.launchpad.net/ubuntu/"
PRIVACY_POLICY_URL="
https://www.ubuntu.com/legal/terms-and-policies/privacy-policy"
VERSION_CODENAME=focal
UBUNTU_CODENAME=focal

import os
import subprocess
import sys
import numpy as np
import xarray as xr
import matplotlib.pyplot as plt
import matplotlib.animation as animation
from matplotlib.artist import Artist
import time
import datetime
from netCDF4 import Dataset as Dataset
import getpass
import cartopy.crs as ccrs
from cartopy.mpl.gridliner import LONGITUDE_FORMATTER, LATITUDE_FORMATTER
import cartopy.feature as cfeat
from matplotlib import cm
import warnings
warnings.filterwarnings('ignore')
from function_wm import xr_opening, mapCARTOPY

projection = ccrs.LambertAzimuthalEqualArea(central_latitude=90,
                                      central_longitude= -90)
fig=plt.figure(figsize=(25,25))
plt.gca()
cornerx=9024309  #meters, from NL.hdr
cornery=cornerx
newcornerx=cornerx/2.
newcornery=newcornerx
newextent=[-newcornerx,newcornerx,-newcornery,newcornery]
ax1 = fig.add_subplot(221,projection=projection)
ax1.coastlines(lw=1)
#ax1.stock_img()
#ax1.set_extent(newextent,projection)
ax2 = fig.add_subplot(222,projection=ccrs.NorthPolarStereo())
ax2.add_feature(cfeat.COASTLINE,edgecolor='black',zorder=10)
#ax2.set_extent(newextent,ccrs.NorthPolarStereo())
ax3 = fig.add_subplot(223,projection=projection)
ax3.coastlines(lw=1)
#ax3.set_extent(newextent,projection)
ax4=  fig.add_subplot(224,projection=projection)
ax4.coastlines(lw=1)

#def anim(i):
name='ice_type_nh_ease2-250_icdr-v2p0_202110181200.nc'
F1=xr_opening(name)
name2='
ice_drift_mosaic_polstereo_sarbased_north_20190101000000-20190102000000.nc.nc
'
F2=xr_opening(name2)
name3='
ice_drift_mosaic_polstereo_sarbased_north_20190104120000-20190105120000.nc.nc
'
F3=xr_opening(name3)

name4='ice_type_nh_ease2-250_icdr-v2p0_202110181200.nc'
F4=xr_opening(name4)
F1['ice_type'].plot(ax=ax1)
ax2.pcolormesh(F2.xc, F2.yc, F2.divergence[0,:,:])
#data['revelant_value'].plot(ax=ax3)
F1['ice_type'].plot(ax=ax4)



Le sam. 6 nov. 2021 ? 21:19, Brett Leach <brettlea at me.com> a ?crit :

> Please post your code (inline, not as an attachment) with any errors that
> occur, Python version, OS, etc. We need more information to assist you.
>
> Brett Leach
>
> > On Nov 6, 2021, at 7:47 PM, Ewen Jamet <ewenjamet73 at gmail.com> wrote:
> >
> > Hello,
> > Does someone can help me i face an issur with plotting on cartopy and it
> is
> > really important that I achieve that tonight.. i would be really greatful
> > Best
> > Ewen Jamet
> > _______________________________________________
> > Tutor maillist  -  Tutor at python.org
> > To unsubscribe or change subscription options:
> > https://mail.python.org/mailman/listinfo/tutor
>
>

From mats at wichmann.us  Sun Nov  7 09:03:24 2021
From: mats at wichmann.us (Mats Wichmann)
Date: Sun, 7 Nov 2021 07:03:24 -0700
Subject: [Tutor] ModuleNotFoundError: No module named 'mysql' in Python
 3.10.0 (default, Nov 6 2021,
 14:56:25) [GCC 4.8.5 20150623 (Red Hat 4.8.5-44)] on linux
In-Reply-To: <CAD7Ssm_kPD7R3b8JVm8MUUnkMqtp=J5J3TZDzTEC9Fa13wk8hQ@mail.gmail.com>
References: <CAD7Ssm_kPD7R3b8JVm8MUUnkMqtp=J5J3TZDzTEC9Fa13wk8hQ@mail.gmail.com>
Message-ID: <976f24e1-2ce9-b157-995d-ed2d26fc7e05@wichmann.us>

On 11/6/21 03:41, Kaushal Shriyan wrote:

> Please guide me and let me know if I am missing anything. 

Well, the error traceback keeps telling you what you're missing:

 > WARNING: pip is configured with locations that require TLS/SSL, 
however the
 > ssl module in Python is not available.
 > WARNING: Retrying (Retry(total=4, connect=None, read=None, redirect=None,
 > status=None)) after connection broken by 'SSLError("Can't connect to 
HTTPS
 > URL because the SSL module is not available.")':

Getting ssl configured right turns out to be a bit tricky. Do you have 
the openssl developer package installed?  You should be able to find 
some more stuff on the Internet on getting this set up.


From mats at wichmann.us  Sun Nov  7 09:54:48 2021
From: mats at wichmann.us (Mats Wichmann)
Date: Sun, 7 Nov 2021 07:54:48 -0700
Subject: [Tutor] Need help on regular expresions
In-Reply-To: <bt7doglanl0tpmpcdnf7m4up80gf4fleru@4ax.com>
References: <CAO1OCwZ=21VjoiDL_j6ASV01cuF92jaDNM8md1tZuXu7jKQ6=A@mail.gmail.com>
 <bt7doglanl0tpmpcdnf7m4up80gf4fleru@4ax.com>
Message-ID: <2575ab55-d657-ef1b-2c64-c0ce18915174@wichmann.us>

On 11/6/21 10:09, Dennis Lee Bieber wrote:
> On Sat, 6 Nov 2021 20:23:45 +0530, Manprit Singh
> <manpritsinghece at gmail.com> declaimed the following:
> 
>>
>> How would I do it with regular expressions ? Since this problem will be
>> very ugly with regular string methods,  that's why I would like to try it
>> with re's.
>>
> 	I wouldn't...
> 
> 	To my understanding, regex do not do COUNTING, so your first criteria
> is not possible. You CAN specify that a regex matches, say, four
> CONSECUTIVE digits (using \d{4] ), but you can't say "match four SCATTERED
> digits".
> 
> https://docs.microsoft.com/en-us/dotnet/standard/base-types/quantifiers-in-regular-expressions
> 
> 	It also doesn't seem that difficult using string methods...
> 
> -=-=-=-
> 
> TESTTEXT = "aG4cD1_23fg"
> TESTTEXT2 = "Ag4C1_23Fg"
> TESTTEXT3 = "Ag4Cd123Fg"

Just for grins, here's a slightly different take on the same, hopefully 
reinforcing that what first seemed ugly maybe isn't so ugly (by all 
means, do learn regular expressions, though, there are places they are 
valuable, although we keep rehasing the old saw here: "I have a problem. 
I know, I'll use regular expressions". "Now you have two problems!"):

import sys
from collections import Counter
from string import ascii_letters, digits
under = '_'

s = "aG4cD1_23f"
if len(s) != 10:
     print(f"String is not 10 chars long ({len(s)})")
     sys.exit(1)

# set targets
cnt = Counter(letter=5, digit=4, underscore=1)

for l in s:
     if l in ascii_letters:
         cnt['letter'] -= 1
     elif l in digits:
         cnt['digit'] -= 1
     elif l in under:
         cnt['underscore'] -= 1

if any([cnt['underscore'], cnt['digit'], cnt['letter']]):
     print("Invalid string")


From matt.ruffalo at gmail.com  Sun Nov  7 09:13:52 2021
From: matt.ruffalo at gmail.com (Matt Ruffalo)
Date: Sun, 7 Nov 2021 09:13:52 -0500
Subject: [Tutor] ModuleNotFoundError: No module named 'mysql' in Python
 3.10.0 (default, Nov 6 2021,
 14:56:25) [GCC 4.8.5 20150623 (Red Hat 4.8.5-44)] on linux
In-Reply-To: <CAD7Ssm_kPD7R3b8JVm8MUUnkMqtp=J5J3TZDzTEC9Fa13wk8hQ@mail.gmail.com>
References: <CAD7Ssm_kPD7R3b8JVm8MUUnkMqtp=J5J3TZDzTEC9Fa13wk8hQ@mail.gmail.com>
Message-ID: <7b560225-2fc9-0eec-b3f1-7d61d3358b51@gmail.com>

On 06/11/21 05:41, Kaushal Shriyan wrote:
> Hi,
>
> I have downloaded Python 3.10.0 on CentOS Linux release 7.9.2009 (Core). I
> have the below openssl and mariadb package installed on CentOS 7.9
>
> # rpm -qa | grep openssl
> openssl-libs-1.0.2k-22.el7_9.x86_64
> openssl-devel-1.0.2k-22.el7_9.x86_64
> openssl-1.0.2k-22.el7_9.x86_64
Hello-

As of Python 3.10, OpenSSL 1.1.1 or newer is required: 
https://www.python.org/dev/peps/pep-0644/

This means that you have effectively compiled Python with no SSL/TLS 
support, hence pip failing to download packages.

MMR...

From wlfraed at ix.netcom.com  Sun Nov  7 12:06:02 2021
From: wlfraed at ix.netcom.com (Dennis Lee Bieber)
Date: Sun, 07 Nov 2021 12:06:02 -0500
Subject: [Tutor] Fwd:  Help
References: <CABtPu_xpM3NvKPVrfdrkxgMOcxRVdJ-4ipAUNsz-fv3ww8PyKQ@mail.gmail.com>
 <771BC361-7C05-4EBD-BE68-974A9E9926B7@me.com>
 <CABtPu_yR=rY2DWAb8njra9Kp62+L1JHasUp3yHaryoG=oeiewA@mail.gmail.com>
 <CABtPu_xpPdfYU_EkvAkC3P=ChD0Gd=Fegb7CkG3d+yWB1Ua1dQ@mail.gmail.com>
Message-ID: <og1gog1qhr7rb4rrf9eht9k80du4b4lqo3@4ax.com>

On Sat, 6 Nov 2021 22:46:57 -0400, Ewen Jamet <ewenjamet73 at gmail.com>
declaimed the following:

>data, as you can see on the screenshot sent, I can not understand why..

	This is a text-only forum -- attachments (other than those that a
blatantly just text) are stripped from posts. If you must use images to
elucidate your problem, you will have to find some image hosting service on
which you can post the image, and then include a URL to that image in your
message text.

	Caveat: If the URL is some hashed value that does not present itself
with an identifiable file-type, many of us will not click on it as it could
be a link to anything.

	http://some.hosting.service/screen_img1.png

is okay.

	http://some.hosting.service/aeE1nMowhAtEv13

will likely not get clicked...


-- 
	Wulfraed                 Dennis Lee Bieber         AF6VN
	wlfraed at ix.netcom.com    http://wlfraed.microdiversity.freeddns.org/


From phillor9 at gmail.com  Sun Nov  7 23:44:32 2021
From: phillor9 at gmail.com (Phil)
Date: Mon, 8 Nov 2021 14:44:32 +1000
Subject: [Tutor] Creating a two dimension set
In-Reply-To: <770240d9-aa5f-6d27-2d5a-4fa5dcf9f8e3@DancesWithMice.info>
References: <rp10og51mqhfh6p1qtttq7c5on0hdcc9bq@4ax.com>
 <YYBcAfcX+f9QEkw+@cskk.homeip.net>
 <770240d9-aa5f-6d27-2d5a-4fa5dcf9f8e3@DancesWithMice.info>
Message-ID: <6cf555da-f48d-b4f8-1c86-2c4a3d06c89a@gmail.com>


I now have access to the Internet again and I thank everyone for their 
advice.

I have now solved the error that I had with a particular Sudoku example. 
It turned out to be an error that only showed itself under certain 
conditions. Not having meaningful function names (the function names are 
still not ideal) and not understanding my own overly complex code that I 
wrote a few years ago was really the cause of my confusion and had 
nothing to do with the use of sets. I don't think that there is any 
advantage in the use of a set of candidates over a list of candidates 
and I think that I'll return to the list method once I get through the 
100s of e-mails that I've just downloaded.

If nothing else, programming keeps me occupied.

-- 

Regards,
Phil


From juliushamilton100 at gmail.com  Mon Nov  8 08:33:28 2021
From: juliushamilton100 at gmail.com (Julius Hamilton)
Date: Mon, 8 Nov 2021 14:33:28 +0100
Subject: [Tutor] html2text expects bytes-like object
Message-ID: <CAEsMKX1EH5c6UaLPBPuh6Lsr3f_VLb+cCV_q4nFRcs2WGpMVGQ@mail.gmail.com>

Hey,

I would like to convert a webpage to plaintext with html2text.

I tried:

import requests
import html2text

r = requests.get("https://www.google.com")

html = r.content

html2text.html2text(html)

But this returns:

TypeError: a bytes-like object is required, not 'str'

In the documentation, it shows the above html2text method working for what
appears to be a string.

Why am I getting the response that I need to pass it a "bytes-like object"?

Thanks very much,
Julius

From alan.gauld at yahoo.co.uk  Mon Nov  8 13:31:16 2021
From: alan.gauld at yahoo.co.uk (Alan Gauld)
Date: Mon, 8 Nov 2021 18:31:16 +0000
Subject: [Tutor] html2text expects bytes-like object
In-Reply-To: <CAEsMKX1EH5c6UaLPBPuh6Lsr3f_VLb+cCV_q4nFRcs2WGpMVGQ@mail.gmail.com>
References: <CAEsMKX1EH5c6UaLPBPuh6Lsr3f_VLb+cCV_q4nFRcs2WGpMVGQ@mail.gmail.com>
Message-ID: <smbqdk$16v3$1@ciao.gmane.io>

On 08/11/2021 13:33, Julius Hamilton wrote:

> html2text.html2text(html)
> 
> But this returns:
> 
> TypeError: a bytes-like object is required, not 'str'

So try converting html to bytes:

> html2text.html2text(bytes(html,encoding='utf8'))

> In the documentation, it shows the above html2text method working for what
> appears to be a string.

Strings and bytes are easily confused visually.

> Why am I getting the response that I need to pass it a "bytes-like object"?

Probably because that's what it needs. A lot of low
level C library functions require a bytes object
rather than a {Python Unicode string. So, if the module
uses such functions, it probably wants a bytes object
passed to it.


-- 
Alan G
Author of the Learn to Program web site
http://www.alan-g.me.uk/
http://www.amazon.com/author/alan_gauld
Follow my photo-blog on Flickr at:
http://www.flickr.com/photos/alangauldphotos



From popity98 at gmail.com  Wed Nov 10 22:57:52 2021
From: popity98 at gmail.com (jimmah9)
Date: Wed, 10 Nov 2021 22:57:52 -0500
Subject: [Tutor] how to analyze thresholded features in an array
Message-ID: <CA+YGNDOtC2vwztnvSe-u+z8H5953+kk+MT0ohaz-jAd4N3AAKA@mail.gmail.com>

I have an array of numerical values (surface pressure on a lat/lon grid).
Using a constant threshold value I'd like to determine the maximum
dimension of each thresholded feature in the array. I've made a mask with
the thresholded value. Any guidance on how to define a feature and
determine geometric properties of each feature? Thanks in advance.

From alan.gauld at yahoo.co.uk  Thu Nov 11 07:17:59 2021
From: alan.gauld at yahoo.co.uk (Alan Gauld)
Date: Thu, 11 Nov 2021 12:17:59 +0000
Subject: [Tutor] how to analyze thresholded features in an array
In-Reply-To: <CA+YGNDOtC2vwztnvSe-u+z8H5953+kk+MT0ohaz-jAd4N3AAKA@mail.gmail.com>
References: <CA+YGNDOtC2vwztnvSe-u+z8H5953+kk+MT0ohaz-jAd4N3AAKA@mail.gmail.com>
Message-ID: <smj1lo$9ss$1@ciao.gmane.io>

On 11/11/2021 03:57, jimmah9 wrote:
> I have an array of numerical values (surface pressure on a lat/lon grid).
> Using a constant threshold value I'd like to determine the maximum
> dimension of each thresholded feature in the array. I've made a mask with
> the thresholded value. Any guidance on how to define a feature and
> determine geometric properties of each feature? Thanks in advance.

Is there a question about Python in there somewhere?
It looks like you are asking about the algorithm or math?

Maybe if you gave us some idea of what your data looks
like and what you are trying to do with it?

Remember, this list is composed of Python programmers
not domain experts in your field. You need to show us
what you are trying to accomplish.

For example, what does "making a mask" mean? It's not
a Python thing... And what does the "maximum dimension
of each thresholded feature" mean? Again, it's not
Python speak.

-- 
Alan G
Author of the Learn to Program web site
http://www.alan-g.me.uk/
http://www.amazon.com/author/alan_gauld
Follow my photo-blog on Flickr at:
http://www.flickr.com/photos/alangauldphotos



From s9814246136 at gmail.com  Fri Nov 12 07:26:12 2021
From: s9814246136 at gmail.com (Sahilpreet Singh)
Date: Fri, 12 Nov 2021 17:56:12 +0530
Subject: [Tutor] Negative step in Python slicing
Message-ID: <CANju1gBy-9FFJYnJ204UO63vKWGN7CwLTRX-0=H4YxNXR2Lp3A@mail.gmail.com>

Hi there,
I am unable to understand how the following works in Python:
mylist[::k]
Where mylist is any iterable and k is any constant value.
It would be very helpful if you can explain with some examples.

From s9814246136 at gmail.com  Fri Nov 12 09:39:49 2021
From: s9814246136 at gmail.com (Sahilpreet Singh)
Date: Fri, 12 Nov 2021 20:09:49 +0530
Subject: [Tutor] Negative step in Python slicing
In-Reply-To: <CANju1gBy-9FFJYnJ204UO63vKWGN7CwLTRX-0=H4YxNXR2Lp3A@mail.gmail.com>
References: <CANju1gBy-9FFJYnJ204UO63vKWGN7CwLTRX-0=H4YxNXR2Lp3A@mail.gmail.com>
Message-ID: <CANju1gD3BFZKz_FXS6mY1+5MS7hvsjCJGO_mWcHeD8b=9f3H0g@mail.gmail.com>

Sorry I wanted to know about this
mylist[::-k]

On Fri, Nov 12, 2021, 17:56 Sahilpreet Singh <s9814246136 at gmail.com> wrote:

> Hi there,
> I am unable to understand how the following works in Python:
> mylist[::k]
> Where mylist is any iterable and k is any constant value.
> It would be very helpful if you can explain with some examples.
>

From alan.gauld at yahoo.co.uk  Fri Nov 12 09:50:01 2021
From: alan.gauld at yahoo.co.uk (Alan Gauld)
Date: Fri, 12 Nov 2021 14:50:01 +0000
Subject: [Tutor] Negative step in Python slicing
In-Reply-To: <CANju1gBy-9FFJYnJ204UO63vKWGN7CwLTRX-0=H4YxNXR2Lp3A@mail.gmail.com>
References: <CANju1gBy-9FFJYnJ204UO63vKWGN7CwLTRX-0=H4YxNXR2Lp3A@mail.gmail.com>
Message-ID: <smluup$n94$1@ciao.gmane.io>

On 12/11/2021 12:26, Sahilpreet Singh wrote:
> I am unable to understand how the following works in Python:
> mylist[::k]
> Where mylist is any iterable and k is any constant value.

Slicing consists of 3 values:

mylist[start:end:step]

where
start defines the first position,
end the last position and
step the number of intermediate entries

In addition it helps to think of the slice operating with
a "knife blade" inserted to the left of the start/end values

Thus mylist[0:10:1]

extracts every element(step=1) from the start at 0 to
the end at 10. ie elements 0 through 9 given the "knife"
rule above.

Each of these parameters has a default value:
start = 0, end = len(mylist), step = 1

So we can define

mylist[::] and get a copy of mylist.
We can also miss out the second colon for the same result.

The step value states how many elements in the original
sequence must be stepped over for each element in the
slice. Thus 2 returns every second element, 3 every third etc.

We can also use negative value to indicate direction
of traversal. Thus -1 indicates an index of the last element,
or a reverse direction of step

Thus mylist[::-1]

returns a reversed list

And mylist[:5:-1]

returns the reverse of the list as far as the 5th element
(using the knife rule the index is on the right side for a
reverse traversal)

Thus turning to your example

mylist[::k]

is the same as:

mylist[0:len(mylist):k]

Lets look at some real examples:

>>> s = list(range(10))

The original list
>>> s[::]
[0, 1, 2, 3, 4, 5, 6, 7, 8, 9]
>>> s[:]
[0, 1, 2, 3, 4, 5, 6, 7, 8, 9]

Start at 3 and get every second item
>>> s[3::2]
[3, 5, 7, 9]

Reverse the list
>>> s[::-1]
[9, 8, 7, 6, 5, 4, 3, 2, 1, 0]

Start at position 3 but go backwards
>>> s[3::-1]
[3, 2, 1, 0]

End at position 6
>>> s[:6:-1]
[9, 8, 7]

I hope that helps, carry on trying things out
yourself for other cases. slicing is very powerful
and flexible but not always intuitive.

--
Alan G
Author of the Learn to Program web site
http://www.alan-g.me.uk/
http://www.amazon.com/author/alan_gauld
Follow my photo-blog on Flickr at:
http://www.flickr.com/photos/alangauldphotos



From mlb121980 at gmail.com  Fri Nov 12 16:40:46 2021
From: mlb121980 at gmail.com (matt)
Date: Fri, 12 Nov 2021 15:40:46 -0600
Subject: [Tutor] ValueError: invalid literal for int() with base 10: '' is
 outcome in line 89--statSet.addNumber(int(n))
Message-ID: <51D86F03-8568-4FC1-85D5-8ECA30405F6C@hxcore.ol>

   My code is ( i did try to give (int(float(n))) but it didn?t work either):

   ?

   #statistics calc

   from math import sqrt

   ?

   #def stat set funk.

   class StatSet:

   ??? def __init__(self):

   ??????? self.data = 0

   ?

   #def get data

   ??? def getData(self):

   ??????? return self.data

   ?

   #def add num.

   ??? def addNumber(self,x):

   ??????? if isinstance(x,(int,float)):

   ??????????? data = self.data

   ??????????? data.append(x)

   ??????????? self.data = data

   ??????????? return self

   #def mean funk.

   ??? def mean(self):

   ??????? nums = self.data

   ?

   #check (if) cond.

   ??????? if len(nums)>0:

   ???? ???????return sum(nums)/len(nums)

   ??????? else:

   ??????????? return 0

   ?

   #def med funk.

   ??? def median(self):

   ??????? nums = self.data

   ??????? nums.sort()

   ??????? length = len(nums)

   ??????? remainder = length%2

   ??????? med = 0

   ?

   #if to check length

   ??????? if length == 0:

   ??????????? return Non

   ??????? elif remainder ==0:

   ??????????? med = (nums[length//2] + nums[length//2-1])/2

   ??????? else:

   ??????????? med = nums[length//2]

   ??????? return med

   ?

   #def funk. stdDev

   ??? def stdDev(self):

   ??????? data = self.data

   ??????? N = self.count()

   ??????? mean = self.mean()

   ??????? devSum = 0

   ?

   ??????? for i in range(N):

   ??????????? devSum = devSum + (data[i] - mean)**2

   ??????? return sqrt(devSum)

   ?

   #def count funk.

   ??? def count(self):

   ??????? count = len(self.data)

   ??????? return count

   ?

   # def min funk.

   ??? def min(self):

   ??????? nums = self.data

   ??????? nums.sort()

   ??????? minNum = nums[0]

   ??????? return minNum

   ?

   #def max funk.

   ??? def max(self):

   ??????? nums = self.data

   ??????? nums.sort()

   ??????? maxNum = nums[-1]

   ??????? return maxNum

   ?

   #main prog.

   def main():

   ??????? print("Program test of StatSet class")

   ?

   #class constructor

   ??????? statSet = StatSet()

   ??????? while True:

   ??????????? n = input("Enter a number (to quit): ")

   ??????????? if n =="":

   ??????????????? break

   #call addnumber funk.

   ??????? statSet.addNumber(int(n))

   ?????????????????????????

   ????????print("Data: ", statSet.getData())

   ??????? print("Mean: ", statSet.mean())

   ??????? print("Median: ", statSet.median())

   ??????? print("Standard deviation: ", statSet.stdDev())

   ??????? print("Min: ", statSet.min())

   ??????? print("Max: ", statSet.max())

   ??????? print("Data: ", statSet.getData())

   ??????? print("Count: ", statSet.count())

   ?

   ??????? if __name__ == '__main__':

   ??????????? main()

   main()

   ?

   ?

   when I enter values I get an error message at the end for line 89
   ?statSet.addNumber(int(n))?

   Sent from [1]Mail for Windows

   ?

References

   Visible links
   1. https://go.microsoft.com/fwlink/?LinkId=550986

From phillor9 at gmail.com  Sat Nov 13 00:04:43 2021
From: phillor9 at gmail.com (Phil)
Date: Sat, 13 Nov 2021 15:04:43 +1000
Subject: [Tutor] A dictionary question
Message-ID: <6aea6665-372a-55b0-a69e-34f10bcb54a4@gmail.com>

Thank you for taking the time to look at this.

I'd like to find the number of pairs in the rows list of sets. The pair 
sets are {7, 3} and {4, 6} because they appear twice each. I'd also like 
to have count_dict dictionary show the two rows where the sets were 
found. What I have is this:

{'row': 5, 'count': 2, 'set': {4, 6}}

Which shows the last row, the count and the set found. I'd like the 
dictionary to also show where the other set {4, 6} was found which is row 1.

This is my best effort so far. I also tried counter from the collections 
module but I doesn't seem to work with sets, at least I couldn't get it 
to work with sets.

rows = [{7,3},{4,6,8},{7,8},{9,3},{7,3},{4,6,3}]

set_list = [{1, 2}, {1, 3}, {1, 4}, {1, 5}, {1, 6}, {1, 7}, {1, 8}, {1, 9},
 ??????????? {2, 3}, {2, 4}, {2, 5}, {2, 6}, {2, 7}, {2, 8}, {2, 9},
 ??????????? {3, 4}, {3, 5}, {3, 6}, {3, 7}, {3, 8}, {3, 9},
 ??????????? {4, 5}, {4, 6}, {4, 7}, {4, 8}, {4,9},
 ??????????? {5, 6}, {5, 7}, {5, 8}, {5, 9},
 ??????????? {6, 7}, {6, 8}, {6, 9},
 ??????????? {7, 8}, {7, 9},
 ??????????? {8, 9}
 ??????????? ]

count_dict = {}

for i in range(len(set_list)):
 ??? count = 0
 ??? for j in range(6):
 ??????? if set_list[i].issubset(rows[j]):
 ??????????? found_set = set_list[i]
 ??????????? count += 1
 ??????????? count_dict['row'] = j
 ??????????? count_dict['count'] = count
 ??????????? count_dict['set'] = found_set

 ??? if count == 2:
 ??????? print(set_list[i], ' is in row ',count, ' times')
 ??????? print(count_dict)

Thank you again.

-- 
Regards,
Phil


From PyTutor at DancesWithMice.info  Sat Nov 13 00:45:26 2021
From: PyTutor at DancesWithMice.info (dn)
Date: Sat, 13 Nov 2021 18:45:26 +1300
Subject: [Tutor] A dictionary question
In-Reply-To: <6aea6665-372a-55b0-a69e-34f10bcb54a4@gmail.com>
References: <6aea6665-372a-55b0-a69e-34f10bcb54a4@gmail.com>
Message-ID: <1faf831f-e2b8-7035-adc2-f59374486166@DancesWithMice.info>

On 13/11/2021 18.04, Phil wrote:
> Thank you for taking the time to look at this.
> 
> I'd like to find the number of pairs in the rows list of sets. The pair
> sets are {7, 3} and {4, 6} because they appear twice each. I'd also like
> to have count_dict dictionary show the two rows where the sets were
> found. What I have is this:
> 
> {'row': 5, 'count': 2, 'set': {4, 6}}
> 
> Which shows the last row, the count and the set found. I'd like the
> dictionary to also show where the other set {4, 6} was found which is
> row 1.
...

> for i in range(len(set_list)):
> ??? count = 0
> ??? for j in range(6):
> ??????? if set_list[i].issubset(rows[j]):
> ??????????? found_set = set_list[i]
> ??????????? count += 1
> ??????????? count_dict['row'] = j 
> ??????????? count_dict['count'] = count
> ??????????? count_dict['set'] = found_set
> 
> ??? if count == 2:
> ??????? print(set_list[i], ' is in row ',count, ' times')
> ??????? print(count_dict)


What a ghastly exercise. Is it homework?

Note that "count_dict['row'] = j" only allows for one set-location to be
noted. Accordingly, change the value of the dictionary to be a list.
Sometimes the list will only be one item long - which seems like a
waste. However, when the counter goes to 2 (or more), then the list will
contain multiple items.

Declare the list at the same time as the count is reset.

Append the set-location to the list whenever a 'hit' is noted.

The last print() will then look something like:

{'row': [1, 5], 'count': 2, 'set': {4, 6}}


Once you've got that working (and not before - "make it work before you
make it better!", you'll realise that the counter is unnecessary because
the length of the list yields the same information!
-- 
Regards,
=dn

From phillor9 at gmail.com  Sat Nov 13 02:14:36 2021
From: phillor9 at gmail.com (Phil)
Date: Sat, 13 Nov 2021 17:14:36 +1000
Subject: [Tutor] A dictionary question
In-Reply-To: <1faf831f-e2b8-7035-adc2-f59374486166@DancesWithMice.info>
References: <6aea6665-372a-55b0-a69e-34f10bcb54a4@gmail.com>
 <1faf831f-e2b8-7035-adc2-f59374486166@DancesWithMice.info>
Message-ID: <c57880bf-7529-fdd3-5c77-30c5d30f9717@gmail.com>


On 13/11/21 15:45, dn via Tutor wrote:
> What a ghastly exercise. Is it homework?

No, just a project to keep myself occupied. There must be easier way to 
find the two pairs.

>
> Note that "count_dict['row'] = j" only allows for one set-location to be
> noted. Accordingly, change the value of the dictionary to be a list.

Thank you dn, I didn't think of that in my frazzled state.

> The last print() will then look something like:
>
> {'row': [1, 5], 'count': 2, 'set': {4, 6}}

Indeed it does. Thank you again.

-- 

Regards,
Phil


From alan.gauld at yahoo.co.uk  Sat Nov 13 06:04:19 2021
From: alan.gauld at yahoo.co.uk (Alan Gauld)
Date: Sat, 13 Nov 2021 11:04:19 +0000
Subject: [Tutor] ValueError: invalid literal for int() with base 10: ''
 is outcome in line 89--statSet.addNumber(int(n))
In-Reply-To: <51D86F03-8568-4FC1-85D5-8ECA30405F6C@hxcore.ol>
References: <51D86F03-8568-4FC1-85D5-8ECA30405F6C@hxcore.ol>
Message-ID: <smo63j$sg9$1@ciao.gmane.io>

On 12/11/2021 21:40, matt wrote:
>    My code is ( i did try to give (int(float(n))) but it didn?t work either):

Always paste the entire error message not just the summary line.
There is a lot of information contained in the error but we
can't see it if you don't paste the whole thing.

>    #statistics calc

BTW You did notice that there is a statistics module in the
standard library that does all the things you are trying to
do here? You could study the code for that to see how they do it.

>    from math import sqrt

>    class StatSet:
> 
>    ??? def __init__(self):
>    ??????? self.data = 0
> 
>    ??? def getData(self):
>    ??????? return self.data

In Python we don't usually create setters/getters, there is no need.

>    ??? def addNumber(self,x):
> 
>    ??????? if isinstance(x,(int,float)):
>    ??????????? data = self.data
>    ??????????? data.append(x)
>    ??????????? self.data = data


This makes no sense.
self.data is a number, 0 by default.
You cannot append() to a number.

You would need to create self.data as a list in the __init__()


>    ??? def mean(self):
>    ??????? nums = self.data
>    #check (if) cond.

Your comments are just replicating the code, they don't add
anything of value and make the code more cluttered. Use
comments to explain *why* the code does things, not *what* the
code does.

>    ??????? if len(nums)>0:
>    ???? ???????return sum(nums)/len(nums)
>    ??????? else:
>    ??????????? return 0

That might result in confusing or even erroneous results.
It would be better to raise an exception than pass back
a wrong answer!


>    ??? def median(self):
>    ??????? nums = self.data
>    ??????? nums.sort()
>    ??????? length = len(nums)
>    ??????? remainder = length%2
>    ??????? med = 0

>    ??????? if length == 0:
>    ??????????? return Non
>    ??????? elif remainder ==0:
>    ??????????? med = (nums[length//2] + nums[length//2-1])/2
>    ??????? else:
>    ??????????? med = nums[length//2]
>    ??????? return med

>    ??? def stdDev(self):
>    ??????? data = self.data
>    ??????? N = self.count()
>    ??????? mean = self.mean()
>    ??????? devSum = 0

>    ??????? for i in range(N):
>    ??????????? devSum = devSum + (data[i] - mean)**2
>    ??????? return sqrt(devSum)

>    ??? def count(self):
>    ??????? count = len(self.data)
>    ??????? return count

>    ??? def min(self):
>    ??????? nums = self.data
>    ??????? nums.sort()
>    ??????? minNum = nums[0]
>    ??????? return minNum

>    ??? def max(self):
>    ??????? nums = self.data
>    ??????? nums.sort()
>    ??????? maxNum = nums[-1]
>    ??????? return maxNum

You realize there are builtin functions min() and max()
for getting the min and max of a sequence?

def main()
>    ??????? statSet = StatSet()
>    ??????? while True:
>    ??????????? n = input("Enter a number (to quit): ")
>    ??????????? if n =="":
>    ??????????????? break
>    ??????? statSet.addNumber(int(n))

Note that the addNumber() is outside the loop so you
only ever add one number.

The subject line would suggest this is probably where
the error occurs but without seeing the error trace
(and ideally the data entered!) its hard to be sure.

-- 
Alan G
Author of the Learn to Program web site
http://www.alan-g.me.uk/
http://www.amazon.com/author/alan_gauld
Follow my photo-blog on Flickr at:
http://www.flickr.com/photos/alangauldphotos



From learn2program at gmail.com  Sat Nov 13 06:10:36 2021
From: learn2program at gmail.com (Alan Gauld)
Date: Sat, 13 Nov 2021 11:10:36 +0000
Subject: [Tutor] Negative step in Python slicing
In-Reply-To: <CANju1gAaPfzu0Axj5d63Ok6NsKzLQA80B5xJC+6uznt74dMVAw@mail.gmail.com>
References: <CANju1gBy-9FFJYnJ204UO63vKWGN7CwLTRX-0=H4YxNXR2Lp3A@mail.gmail.com>
 <smluup$n94$1@ciao.gmane.io>
 <CANju1gAaPfzu0Axj5d63Ok6NsKzLQA80B5xJC+6uznt74dMVAw@mail.gmail.com>
Message-ID: <bacbd689-2339-1d27-f93d-6b55f56fb1d0@yahoo.co.uk>

Always use Reply-All or Rely-List when responding to tutor emails.

On 13/11/2021 01:13, Sahilpreet Singh wrote:
> Thanks Alan?
> But can you explain some cases where step is like -2 or -3.

It is exactly like -1 except it steps by the number shown.
In the same way as 2 or 3 step forward.

The easiest way is to try it in the interpreter:

>>> s = [1,2,3,4,5,6,7,8,9]
>>> s[::-2]? #every second item in reverse...
[9, 7, 5, 3, 1]
>>> s[::-3]? #every third item in reverse...
[9, 6, 3]
>>>

As I said...


>     Slicing consists of 3 values:
>
>     mylist[start:end:step]
>
>     where
>     start defines the first position,
>     end the last position and
>     step the number of intermediate entries
>
>     ...
>

>     Each of these parameters has a default value:
>     start = 0, end = len(mylist), step = 1
>
>
...


>     The step value states how many elements in the original
>     sequence must be stepped over for each element in the
>     slice. Thus 2 returns every second element, 3 every third etc.
>
>     We can also use negative value to indicate direction
>     of traversal. Thus -1 indicates an index of the last element,
>     or a reverse direction of step
>
>     Thus mylist[::-1]
>
>     returns a reversed list
>
>     >>> s[:]
>     [0, 1, 2, 3, 4, 5, 6, 7, 8, 9]
>
>     Start at 3 and get every second item
>     >>> s[3::2]
>     [3, 5, 7, 9]
>
>     Reverse the list
>     >>> s[::-1]
>     [9, 8, 7, 6, 5, 4, 3, 2, 1, 0]
>
>     -- 
>
Alan G
Author of the Learn to Program web site
http://www.alan-g.me.uk/
http://www.amazon.com/author/alan_gauld
Follow my photo-blog on Flickr at:
http://www.flickr.com/photos/alangauldphotos


From s9814246136 at gmail.com  Sat Nov 13 09:06:58 2021
From: s9814246136 at gmail.com (Sahilpreet Singh)
Date: Sat, 13 Nov 2021 19:36:58 +0530
Subject: [Tutor] Negative step in Python slicing
In-Reply-To: <bacbd689-2339-1d27-f93d-6b55f56fb1d0@yahoo.co.uk>
References: <CANju1gBy-9FFJYnJ204UO63vKWGN7CwLTRX-0=H4YxNXR2Lp3A@mail.gmail.com>
 <smluup$n94$1@ciao.gmane.io>
 <CANju1gAaPfzu0Axj5d63Ok6NsKzLQA80B5xJC+6uznt74dMVAw@mail.gmail.com>
 <bacbd689-2339-1d27-f93d-6b55f56fb1d0@yahoo.co.uk>
Message-ID: <CANju1gANV7Y2X1Lg2=EzB6WFZG7suk-SJ=15ZiWpcD2ZQmKe6g@mail.gmail.com>

Thanks for your help.This community is best.

On Sat, Nov 13, 2021, 16:40 Alan Gauld <learn2program at gmail.com> wrote:

> Always use Reply-All or Rely-List when responding to tutor emails.
>
> On 13/11/2021 01:13, Sahilpreet Singh wrote:
> > Thanks Alan
> > But can you explain some cases where step is like -2 or -3.
>
> It is exactly like -1 except it steps by the number shown.
> In the same way as 2 or 3 step forward.
>
> The easiest way is to try it in the interpreter:
>
> >>> s = [1,2,3,4,5,6,7,8,9]
> >>> s[::-2]  #every second item in reverse...
> [9, 7, 5, 3, 1]
> >>> s[::-3]  #every third item in reverse...
> [9, 6, 3]
> >>>
>
> As I said...
>
>
> >     Slicing consists of 3 values:
> >
> >     mylist[start:end:step]
> >
> >     where
> >     start defines the first position,
> >     end the last position and
> >     step the number of intermediate entries
> >
> >     ...
> >
>
> >     Each of these parameters has a default value:
> >     start = 0, end = len(mylist), step = 1
> >
> >
> ...
>
>
> >     The step value states how many elements in the original
> >     sequence must be stepped over for each element in the
> >     slice. Thus 2 returns every second element, 3 every third etc.
> >
> >     We can also use negative value to indicate direction
> >     of traversal. Thus -1 indicates an index of the last element,
> >     or a reverse direction of step
> >
> >     Thus mylist[::-1]
> >
> >     returns a reversed list
> >
> >     >>> s[:]
> >     [0, 1, 2, 3, 4, 5, 6, 7, 8, 9]
> >
> >     Start at 3 and get every second item
> >     >>> s[3::2]
> >     [3, 5, 7, 9]
> >
> >     Reverse the list
> >     >>> s[::-1]
> >     [9, 8, 7, 6, 5, 4, 3, 2, 1, 0]
> >
> >     --
> >
> Alan G
> Author of the Learn to Program web site
> http://www.alan-g.me.uk/
> http://www.amazon.com/author/alan_gauld
> Follow my photo-blog on Flickr at:
> http://www.flickr.com/photos/alangauldphotos
>
>

From coskunarslan at yahoo.com  Sat Nov 13 09:43:59 2021
From: coskunarslan at yahoo.com (coskun arslan)
Date: Sat, 13 Nov 2021 14:43:59 +0000 (UTC)
Subject: [Tutor] prime numbers
References: <1604045709.1384989.1636814639752.ref@mail.yahoo.com>
Message-ID: <1604045709.1384989.1636814639752@mail.yahoo.com>

Want to list primes to 20.Where is mistake??
my_list=[i for i in range(2,21)]for i in my_list:? ? ? ?for k in range(2,i):? ? ? ? ? ? ? if i%k==0:? ? ? ? ? ? ? ? ? my_list.remove(i)print(my_list)
It gives eror List.remove(i) i is not in list.What is wronge?? ? ? ? ?

Android?de Yahoo Postadan g?nderildi

From alan.gauld at yahoo.co.uk  Sat Nov 13 19:16:44 2021
From: alan.gauld at yahoo.co.uk (Alan Gauld)
Date: Sun, 14 Nov 2021 00:16:44 +0000
Subject: [Tutor] prime numbers
In-Reply-To: <1604045709.1384989.1636814639752@mail.yahoo.com>
References: <1604045709.1384989.1636814639752.ref@mail.yahoo.com>
 <1604045709.1384989.1636814639752@mail.yahoo.com>
Message-ID: <smpkhd$srj$1@ciao.gmane.io>

On 13/11/2021 14:43, coskun arslan via Tutor wrote:
Please always post code in plain text, the HTML text gets messed
up, and formatting is very important in Python.

In this case I'll try to reformat it as you probably had it...


my_list=[i for i in range(2,21)]
for i in my_list:
? ? ? ?for k in range(2,i):
? ? ? ? ? ? ? if i%k==0:
? ? ? ? ? ? ? ? ? my_list.remove(i)
print(my_list)

> It gives eror List.remove(i) i is not in list.What is wronge?? ? ? ? ?

Please always post the full error text not a summary,
there is a lot of useful information contained in the
error text.

But in this case you are iterating over my list while at the
same time removing elements of the list. That's a bit like
cutting down the branch of the tree that you are sitting on.

Python goes looking for the item at position 6, say,  but
in the meantime you have deleted items 3 and 4 so item 6
is no longer at position 6. Python gets confused!
To fix that you can iterate over a copy of the list
(mylist[:] is an easy way to create a copy) and remove
from the original list.

By the way, there are much more efficient algorithms for
finding prime numbers. For example:
Think about how high you need to go to find the factors.
Take 24 as an example:
(1,24),(2,12),(3,8),(4,6),(6,4), ...
but wait, 6,4 is the same pair as 4,6.
We are repeating ourselves. So we only need to test
up to the square root of the target, int(24**0.5) => 4.

That saves a bunch of tests.

But there are even more powerful algorithms you can use.
Try a google search...

-- 
Alan G
Author of the Learn to Program web site
http://www.alan-g.me.uk/
http://www.amazon.com/author/alan_gauld
Follow my photo-blog on Flickr at:
http://www.flickr.com/photos/alangauldphotos



From phillor9 at gmail.com  Mon Nov 15 02:30:40 2021
From: phillor9 at gmail.com (Phil)
Date: Mon, 15 Nov 2021 17:30:40 +1000
Subject: [Tutor] A dictionary question
In-Reply-To: <1faf831f-e2b8-7035-adc2-f59374486166@DancesWithMice.info>
References: <6aea6665-372a-55b0-a69e-34f10bcb54a4@gmail.com>
 <1faf831f-e2b8-7035-adc2-f59374486166@DancesWithMice.info>
Message-ID: <ed2406d1-c3a2-ad8d-d685-55e3b38ae093@gmail.com>

Thank you once again for taking the time to look at this.

I've refined the requirements from my previous question. What I need is 
to check for the existence of a pair of sets from the set_list in the 
row list of sets twice and not in any other set. {4,6} in the first row 
list of sets fulfills the requirement and there are no sets in the 
second row list of sets that meets this requirement.

The code that follows is the basis of what I've been working on. The 
print statements show what's needed but I cannot think of a clever way 
to code this requirement. I've experimented with dictionaries but I've 
come to the conclusion that a boolean test is what's needed to weed out 
the sets that don't meet the requirements.

Any code snippets or ideas will be greatly appreciated.

#row = [{7,3},{5},{4,8,6},{7,8},{1},{9,3},{7,9},{4,6,3},{2}]
row = [{5},{6},{3},{4,7,5},{1,2,4,5},{1,7,5},{1,2,4,7,9},{8},{1,2,4,7,9}]

set_list = [{1, 2}, {1, 3}, {1, 4}, {1, 5}, {1, 6}, {1, 7}, {1, 8}, {1, 9},
 ??????????? {2, 3}, {2, 4}, {2, 5}, {2, 6}, {2, 7}, {2, 8}, {2, 9},
 ??????????? {3, 4}, {3, 5}, {3, 6}, {3, 7}, {3, 8}, {3, 9},
 ??????????? {4, 5}, {4, 6}, {4, 7}, {4, 8}, {4,9},
 ??????????? {5, 6}, {5, 7}, {5, 8}, {5, 9},
 ??????????? {6, 7}, {6, 8}, {6, 9},
 ??????????? {7, 8}, {7, 9},
 ??????????? {8, 9}
 ??????????? ]

count_dict = {}

for i in range(len(set_list)):
 ??? count = 0
 ??? row_list = []
 ??? for j in range(9):
 ??????? if set_list[i].issubset(row[j]) and len(row[j]) > 2:
 ??????????? row_list.append(j)
 ??????????? count += 1
 ??????????? count_dict['row'] = row_list
 ??????????? count_dict['count'] = count
 ??????????? count_dict['set'] = set_list[i]

 ??????? print(set_list[i], ' ', row_list)
 ??????? print(count_dict)

-- 

Regards,
Phil


From phillor9 at gmail.com  Mon Nov 15 03:00:48 2021
From: phillor9 at gmail.com (Phil)
Date: Mon, 15 Nov 2021 18:00:48 +1000
Subject: [Tutor] A dictionary question
In-Reply-To: <1faf831f-e2b8-7035-adc2-f59374486166@DancesWithMice.info>
References: <6aea6665-372a-55b0-a69e-34f10bcb54a4@gmail.com>
 <1faf831f-e2b8-7035-adc2-f59374486166@DancesWithMice.info>
Message-ID: <deae3f08-ffb2-09b5-77fd-1ce764e6c3cc@gmail.com>

I think I have to start from scratch.

The same pair of numbers has to exist twice in the row set plus each 
number (not a pair set) cannot exist in any other row set. That being 
the case, I now have to rethink the idea of using a pair list lookup 
table which is cumbersome and tedious to debug.

-- 

Regards,
Phil


From abba6 at mac.com  Mon Nov 15 05:05:45 2021
From: abba6 at mac.com (=?utf-8?Q?Asbj=C3=B8rn_Bakken?=)
Date: Mon, 15 Nov 2021 11:05:45 +0100
Subject: [Tutor] First try
Message-ID: <CDD838E3-20A2-46B9-91F5-FBA2F1E26368@mac.com>

Hi there,

I am brand-new to python. In my younger days I did some programming in Fortran and Cobolt (ages ago) but it is all lost. So I started out with Python for Kids for dummies.It worked nice on my macpro untill I upgraded to the latest IOS 12.0.1. Useing 2.7 (continued to work) but IDLE went in black (useless).

All because 2.7 is no longer supported?

Anything I can do or must I jump to latest version of Python?

ASbak

From vinay.g_ece2019 at svce.edu.in  Mon Nov 15 13:01:07 2021
From: vinay.g_ece2019 at svce.edu.in (481 Vinay)
Date: Mon, 15 Nov 2021 23:31:07 +0530
Subject: [Tutor] Tutor Digest, Vol 213, Issue 17
In-Reply-To: <mailman.4.1636909202.21255.tutor@python.org>
References: <mailman.4.1636909202.21255.tutor@python.org>
Message-ID: <CAHg-0kcGCywupPRqggVXG8LgRZ7=dH_0DeeLRic0On1ALENx7A@mail.gmail.com>

Code for this one

On Sun, Nov 14, 2021, 10:31 PM <tutor-request at python.org> wrote:

> Send Tutor mailing list submissions to
>         tutor at python.org
>
> To subscribe or unsubscribe via the World Wide Web, visit
>         https://mail.python.org/mailman/listinfo/tutor
> or, via email, send a message with subject or body 'help' to
>         tutor-request at python.org
>
> You can reach the person managing the list at
>         tutor-owner at python.org
>
> When replying, please edit your Subject line so it is more specific
> than "Re: Contents of Tutor digest..."
> Today's Topics:
>
>    1. prime numbers (coskun arslan)
>    2. Re: prime numbers (Alan Gauld)
>
>
>
> ---------- Forwarded message ----------
> From: coskun arslan <coskunarslan at yahoo.com>
> To: "tutor at python.org" <tutor at python.org>
> Cc:
> Bcc:
> Date: Sat, 13 Nov 2021 14:43:59 +0000 (UTC)
> Subject: [Tutor] prime numbers
> Want to list primes to 20.Where is mistake?
> my_list=[i for i in range(2,21)]for i in my_list:       for k in
> range(2,i):              if i%k==0:
> my_list.remove(i)print(my_list)
> It gives eror List.remove(i) i is not in list.What is wronge?
>
> Android?de Yahoo Postadan g?nderildi
>
>
>
> ---------- Forwarded message ----------
> From: Alan Gauld <alan.gauld at yahoo.co.uk>
> To: tutor at python.org
> Cc:
> Bcc:
> Date: Sun, 14 Nov 2021 00:16:44 +0000
> Subject: Re: [Tutor] prime numbers
> On 13/11/2021 14:43, coskun arslan via Tutor wrote:
> Please always post code in plain text, the HTML text gets messed
> up, and formatting is very important in Python.
>
> In this case I'll try to reformat it as you probably had it...
>
>
> my_list=[i for i in range(2,21)]
> for i in my_list:
>        for k in range(2,i):
>               if i%k==0:
>                   my_list.remove(i)
> print(my_list)
>
> > It gives eror List.remove(i) i is not in list.What is wronge?
>
> Please always post the full error text not a summary,
> there is a lot of useful information contained in the
> error text.
>
> But in this case you are iterating over my list while at the
> same time removing elements of the list. That's a bit like
> cutting down the branch of the tree that you are sitting on.
>
> Python goes looking for the item at position 6, say,  but
> in the meantime you have deleted items 3 and 4 so item 6
> is no longer at position 6. Python gets confused!
> To fix that you can iterate over a copy of the list
> (mylist[:] is an easy way to create a copy) and remove
> from the original list.
>
> By the way, there are much more efficient algorithms for
> finding prime numbers. For example:
> Think about how high you need to go to find the factors.
> Take 24 as an example:
> (1,24),(2,12),(3,8),(4,6),(6,4), ...
> but wait, 6,4 is the same pair as 4,6.
> We are repeating ourselves. So we only need to test
> up to the square root of the target, int(24**0.5) => 4.
>
> That saves a bunch of tests.
>
> But there are even more powerful algorithms you can use.
> Try a google search...
>
> --
> Alan G
> Author of the Learn to Program web site
> http://www.alan-g.me.uk/
> http://www.amazon.com/author/alan_gauld
> Follow my photo-blog on Flickr at:
> http://www.flickr.com/photos/alangauldphotos
>
>
>
> _______________________________________________
> Tutor maillist  -  Tutor at python.org
> https://mail.python.org/mailman/listinfo/tutor
>

From alan.gauld at yahoo.co.uk  Mon Nov 15 14:02:32 2021
From: alan.gauld at yahoo.co.uk (Alan Gauld)
Date: Mon, 15 Nov 2021 19:02:32 +0000
Subject: [Tutor] First try
In-Reply-To: <CDD838E3-20A2-46B9-91F5-FBA2F1E26368@mac.com>
References: <CDD838E3-20A2-46B9-91F5-FBA2F1E26368@mac.com>
Message-ID: <smuas9$4ot$1@ciao.gmane.io>

On 15/11/2021 10:05, Asbj?rn Bakken via Tutor wrote:

> I started out with Python for Kids for dummies.It worked nice on my macpro

I don;t use Python on a mac but...

>  untill I upgraded to the latest IOS 12.0.1. 
> Useing 2.7 (continued to work) but IDLE went in black (useless).

2.7 is indeed out of support but it should still work.
Can you try it in the terminal app and see if it works there?
It may be a Tcl/Tk issue which is causing IDLE to fail.
(IDLE is built using tkinter which, in turn, uses Tcl/Tk)

> Anything I can do or must I jump to latest version of Python?

It should work, but I'd strongly encourage you to jump to
Python 3. Your tutorial might not work of course but there
are many, many, online tutorials(including mine!) based on
Python 3.

-- 
Alan G
Author of the Learn to Program web site
http://www.alan-g.me.uk/
http://www.amazon.com/author/alan_gauld
Follow my photo-blog on Flickr at:
http://www.flickr.com/photos/alangauldphotos



From mats at wichmann.us  Mon Nov 15 14:06:51 2021
From: mats at wichmann.us (Mats Wichmann)
Date: Mon, 15 Nov 2021 12:06:51 -0700
Subject: [Tutor] A dictionary question
In-Reply-To: <deae3f08-ffb2-09b5-77fd-1ce764e6c3cc@gmail.com>
References: <6aea6665-372a-55b0-a69e-34f10bcb54a4@gmail.com>
 <1faf831f-e2b8-7035-adc2-f59374486166@DancesWithMice.info>
 <deae3f08-ffb2-09b5-77fd-1ce764e6c3cc@gmail.com>
Message-ID: <c4f68c2a-4144-8cfe-4d0f-ea5b33622950@wichmann.us>


On 11/15/21 01:00, Phil wrote:
> I think I have to start from scratch.
> 
> The same pair of numbers has to exist twice in the row set plus each 
> number (not a pair set) cannot exist in any other row set. That being 
> the case, I now have to rethink the idea of using a pair list lookup 
> table which is cumbersome and tedious to debug.
> 

Doesn't sound too bad.

Count how many times the pairs appear in the various elements of your 
rowlist. I'd probably do something like this:

from collections import Counter

pairs = Counter()

for s in set_list:
     for r in row:
         if s.issubset(r):
             pairs[tuple(sorted(s))] += 1

since sets are unordered I would sort to get a reproducible pair, then 
have to convert to tuple so it's hashable and able to serve as a 
dictionary key.

Now walk through the counts, finding candidates - namely pairs with 
counts of 2 (or whatever number you pick), and do a quick pass counting 
up how many times each item of the pair appears in the rowlist elements. 
  If those counts aren't also two, your candidate is eliminated.

Remembering that Counter is a dict, you can start this loop like:

for item, count in pairs.items():

does this help?

From alan.gauld at yahoo.co.uk  Mon Nov 15 14:09:46 2021
From: alan.gauld at yahoo.co.uk (Alan Gauld)
Date: Mon, 15 Nov 2021 19:09:46 +0000
Subject: [Tutor] Tutor Digest, Vol 213, Issue 17
In-Reply-To: <CAHg-0kcGCywupPRqggVXG8LgRZ7=dH_0DeeLRic0On1ALENx7A@mail.gmail.com>
References: <mailman.4.1636909202.21255.tutor@python.org>
 <CAHg-0kcGCywupPRqggVXG8LgRZ7=dH_0DeeLRic0On1ALENx7A@mail.gmail.com>
Message-ID: <smub9q$ukj$1@ciao.gmane.io>

On 15/11/2021 18:01, 481 Vinay wrote:
> Code for this one

I'm not sure what you mean by that?

But please don't repost the entire digest (only two
messages here but often much more). Many people pay
for their internet by the byte so sending stuff we
have all seen already is not helpful.

Select the parts that are relevant to your message
and send those for context.

Alan G.
Moderator


From mats at wichmann.us  Mon Nov 15 14:14:23 2021
From: mats at wichmann.us (Mats Wichmann)
Date: Mon, 15 Nov 2021 12:14:23 -0700
Subject: [Tutor] First try
In-Reply-To: <CDD838E3-20A2-46B9-91F5-FBA2F1E26368@mac.com>
References: <CDD838E3-20A2-46B9-91F5-FBA2F1E26368@mac.com>
Message-ID: <d71eec06-c3fc-07aa-f6b5-84ceb428bc8c@wichmann.us>

On 11/15/21 03:05, Asbj?rn Bakken via Tutor wrote:
> Hi there,
> 
> I am brand-new to python. In my younger days I did some programming in Fortran and Cobolt (ages ago) but it is all lost. So I started out with Python for Kids for dummies.It worked nice on my macpro untill I upgraded to the latest IOS 12.0.1. Useing 2.7 (continued to work) but IDLE went in black (useless).
> 
> All because 2.7 is no longer supported?
> 
> Anything I can do or must I jump to latest version of Python?

don't use the built-in Python on macOS.


There are several ways to get a usable Python3 onto the Mac, not least 
of which is grabbing an installer from python.org.

As Alan surmised, there was indeed a problem that broke tk, which breaks 
the binding tkinter, which IDLE is built on.   There's a lengthy thread 
on the Python bugtracker and elsewhere on this, and I believe new 
installers were issued which let IDLE work on 12.x - I think it's a 
workaround for now, until tk itself gets fixed - but the tk folks can't 
fix the one that's pre-installed on macOS, just the version that will be 
bundled with new Python installers.

some notes here:

https://blog.python.org/2021/11/

and the general page may be useful too:

https://docs.python.org/3/using/mac.html



From phillor9 at gmail.com  Mon Nov 15 15:57:32 2021
From: phillor9 at gmail.com (Phil)
Date: Tue, 16 Nov 2021 06:57:32 +1000
Subject: [Tutor] A dictionary question
In-Reply-To: <c4f68c2a-4144-8cfe-4d0f-ea5b33622950@wichmann.us>
References: <6aea6665-372a-55b0-a69e-34f10bcb54a4@gmail.com>
 <1faf831f-e2b8-7035-adc2-f59374486166@DancesWithMice.info>
 <deae3f08-ffb2-09b5-77fd-1ce764e6c3cc@gmail.com>
 <c4f68c2a-4144-8cfe-4d0f-ea5b33622950@wichmann.us>
Message-ID: <c83b5118-f967-bee5-4568-2a9d0f146467@gmail.com>


On 16/11/21 05:06, Mats Wichmann wrote:
>
> On 11/15/21 01:00, Phil wrote:
>> I think I have to start from scratch.
>>
>> The same pair of numbers has to exist twice in the row set plus each 
>> number (not a pair set) cannot exist in any other row set. That being 
>> the case, I now have to rethink the idea of using a pair list lookup 
>> table which is cumbersome and tedious to debug.
>>
>
> Doesn't sound too bad.
>
> Count how many times the pairs appear in the various elements of your 
> rowlist. I'd probably do something like this:

Thank you Mats,

To find a solution to a problem, a university lecturer was fond of 
telling his first year students to explain the problem to their dog if 
they didn't have anyone else to talk to. This list is my dog and I don't 
always post my questions.

Anyway, I had a bright idea (after I posted my question) that I could 
use a list of dictionaries and make two passes through the row list; 
once to search for pairs and a second time to eliminate those that have 
members that also appear in another set. I had experimented with counter 
from the collections module but ran into problems with counting sets. I 
knew that it worked with tuples but it didn't occur to me to convert the 
set to a tuple.

I'm about to move on from this campsite and I won't have Internet access 
for three or four days, however, I expect to make some progress with 
this project thanks to your reply.

-- 
Regards,
Phil


From juliushamilton100 at gmail.com  Mon Nov 15 14:02:56 2021
From: juliushamilton100 at gmail.com (Julius Hamilton)
Date: Mon, 15 Nov 2021 20:02:56 +0100
Subject: [Tutor] A simple sentence reader with pre-established libraries
Message-ID: <CAEsMKX2+wOLDd_iqXv0Li6fudvL6wDjGge9cYJ_pQhW8Y6-x4w@mail.gmail.com>

Hey,

I would like to try to make a simple sentence-by-sentence reader, using as
many pre-established software libraries as possible, to keep the code very
simple.

First, I get the html and extract the plaintext. I can do this with wget or
python requests, then in theory html2text. However, I have found html2text
sometimes breaks sentences into different
lines, like how this sentence I am writing is broken. I?m not sure if this
is a bug or if there?s some option I don?t know about.

However, I have a Beautiful Soup method to do this as well:
https://stackoverflow.com/questions/69680184/how-do-i-retrieve-the-text-of-a-webpage-without-sentences-being-broken-by-newlin

Then, I just wanted to segment the text on sentences. I?ll probably use
Spacy, since it seems to be the most modern, either rule-based or with AI.
But I also have used NLTK in the past.

At that point, I just want to create the simplest command line application
which shows the list one element at a time, with simple navigation options
like backwards and forwards and quit, and maybe save progress.

Here?s the essential question: instead of writing this myself, what are the
chances that there is yet again some great pre-existing tool out there that
I could make use of? Is there some software library where with one line of
code I could ?read? a list, or a plaintext document, at the command line,
sentence by sentence, or element by element, with or without some
navigation functionalities?

Thanks very much,
Julius

From cs at cskk.id.au  Mon Nov 15 18:09:42 2021
From: cs at cskk.id.au (Cameron Simpson)
Date: Tue, 16 Nov 2021 10:09:42 +1100
Subject: [Tutor] First try
In-Reply-To: <d71eec06-c3fc-07aa-f6b5-84ceb428bc8c@wichmann.us>
References: <d71eec06-c3fc-07aa-f6b5-84ceb428bc8c@wichmann.us>
Message-ID: <YZLotmFHhafFfe87@cskk.homeip.net>

On 15Nov2021 12:14, Mats Wichmann <mats at wichmann.us> wrote:
>On 11/15/21 03:05, Asbj?rn Bakken via Tutor wrote:
>>Hi there,
>>
>>I am brand-new to python. In my younger days I did some programming in Fortran and Cobolt (ages ago) but it is all lost. So I started out with Python for Kids for dummies.It worked nice on my macpro untill I upgraded to the latest IOS 12.0.1. Useing 2.7 (continued to work) but IDLE went in black (useless).
>>
>>All because 2.7 is no longer supported?

Perhaps. You should shift to Python 3 anyway. The differences are small 
if you're just starting out; the most overt one is that print() is now a 
function and requires parentheses.

You Mac will have a "python3" command which runs a modern version of 
Python; it should be quite recent. The plain "python" command runs 
Python 2.

>>Anything I can do or must I jump to latest version of Python?
>
>don't use the built-in Python on macOS.

Indeed, althought the Python 3 on a Mac is normally pretty current (as 
of the OS version you are running).

>There are several ways to get a usable Python3 onto the Mac, not least 
>of which is grabbing an installer from python.org.

By coincidence, I did exactly that on Monday. Works fine!

But if you just need to shift to Python 3, the "python3" already on your 
Mac will also work fine.

Cheers,
Cameron Simpson <cs at cskk.id.au>

From phillor9 at gmail.com  Tue Nov 16 00:07:25 2021
From: phillor9 at gmail.com (Phil)
Date: Tue, 16 Nov 2021 15:07:25 +1000
Subject: [Tutor] A dictionary question
In-Reply-To: <c4f68c2a-4144-8cfe-4d0f-ea5b33622950@wichmann.us>
References: <6aea6665-372a-55b0-a69e-34f10bcb54a4@gmail.com>
 <1faf831f-e2b8-7035-adc2-f59374486166@DancesWithMice.info>
 <deae3f08-ffb2-09b5-77fd-1ce764e6c3cc@gmail.com>
 <c4f68c2a-4144-8cfe-4d0f-ea5b33622950@wichmann.us>
Message-ID: <678af609-ee0b-d298-bc6a-ec12bc96ed57@gmail.com>

Just a quick one while I stop for afternoon tea.

Using the example provide by Mats, if I print(pairs) I get:

Counter({(4, 6): 2, (3, 4): 1, (3, 6): 1 etc.

How would I print the pairs so they look like this:

(4,6) 2
(3,4) 1
(3,6) 1

My feeble attempt is under the example code. I have looked at a couple 
of collections tutorials but I cannot relate what I'm seeing to the 
example below.

I'm also wondering how I might do something like this:

if count == 2:

 ??? do this

row = [{7,3},{5},{4,6,8},{7,8},{1},{9,3},{7,9},{4,6,3},{2}]
#row = [{5},{6},{3},{4,7,5},{1,2,4,5},{1,7,5},{1,2,4,7,9},{8},{1,2,4,7,9}]

set_list = [{1, 2}, {1, 3}, {1, 4}, {1, 5}, {1, 6}, {1, 7}, {1, 8}, {1, 9},
 ??????????? {2, 3}, {2, 4}, {2, 5}, {2, 6}, {2, 7}, {2, 8}, {2, 9},
 ??????????? {3, 4}, {3, 5}, {3, 6}, {3, 7}, {3, 8}, {3, 9},
 ??????????? {4, 5}, {4, 6}, {4, 7}, {4, 8}, {4,9},
 ??????????? {5, 6}, {5, 7}, {5, 8}, {5, 9},
 ??????????? {6, 7}, {6, 8}, {6, 9},
 ??????????? {7, 8}, {7, 9},
 ??????????? {8, 9}
 ??????????? ]

from collections import Counter

pairs = Counter()

for s in set_list:
 ??? for r in row:
 ??????? if s.issubset(r):
 ??????????? pairs[tuple(sorted(s))] += 1

print(pairs)

for i in range(9):
 ??? print(pairs[i])

-- 
Regards,
Phil


From martin at linux-ip.net  Tue Nov 16 01:11:42 2021
From: martin at linux-ip.net (Martin A. Brown)
Date: Mon, 15 Nov 2021 22:11:42 -0800
Subject: [Tutor] A dictionary question
In-Reply-To: <678af609-ee0b-d298-bc6a-ec12bc96ed57@gmail.com>
References: <6aea6665-372a-55b0-a69e-34f10bcb54a4@gmail.com>
 <1faf831f-e2b8-7035-adc2-f59374486166@DancesWithMice.info>
 <deae3f08-ffb2-09b5-77fd-1ce764e6c3cc@gmail.com>
 <c4f68c2a-4144-8cfe-4d0f-ea5b33622950@wichmann.us>
 <678af609-ee0b-d298-bc6a-ec12bc96ed57@gmail.com>
Message-ID: <3c57b666-6ee-cb21-9bcc-67a4bdb7a545@wonderfrog.net>


Hello,

> Just a quick one while I stop for afternoon tea.
> 
> Using the example provide by Mats, if I print(pairs) I get:
> 
> Counter({(4, 6): 2, (3, 4): 1, (3, 6): 1 etc.
> 
> How would I print the pairs so they look like this:
> 
> (4,6) 2
> (3,4) 1
> (3,6) 1

The collections.Counter behaves like a dictionary.  Same methods 
should work.  So, try something like these basic loops that take 
advantage of the items() method.

  c = Counter({(4, 6): 2, (3, 4): 1, (3, 6): 1})
  
  # -- loop through all of the key, value items in the dict-like object
  for k, v in c.items(): 
      print( k, v)

  # -- same but only print where the counter for that entry is 2
  for k, v in c.items(): 
      if v == 2: 
          print( k, v) 

Good luck, enjoy the tea (for a change of pace) and leave your 
dictionaries cleaner than when you arrived.  Only you can stop code 
rot!

-Martin


> My feeble attempt is under the example code. I have looked at a couple of
> collections tutorials but I cannot relate what I'm seeing to the example
> below.
> 
> I'm also wondering how I might do something like this:
> 
> if count == 2:
> 
> ??? do this
> 
> row = [{7,3},{5},{4,6,8},{7,8},{1},{9,3},{7,9},{4,6,3},{2}]
> #row = [{5},{6},{3},{4,7,5},{1,2,4,5},{1,7,5},{1,2,4,7,9},{8},{1,2,4,7,9}]
> 
> set_list = [{1, 2}, {1, 3}, {1, 4}, {1, 5}, {1, 6}, {1, 7}, {1, 8}, {1, 9},
> ??????????? {2, 3}, {2, 4}, {2, 5}, {2, 6}, {2, 7}, {2, 8}, {2, 9},
> ??????????? {3, 4}, {3, 5}, {3, 6}, {3, 7}, {3, 8}, {3, 9},
> ??????????? {4, 5}, {4, 6}, {4, 7}, {4, 8}, {4,9},
> ??????????? {5, 6}, {5, 7}, {5, 8}, {5, 9},
> ??????????? {6, 7}, {6, 8}, {6, 9},
> ??????????? {7, 8}, {7, 9},
> ??????????? {8, 9}
> ??????????? ]
> 
> from collections import Counter
> 
> pairs = Counter()
> 
> for s in set_list:
> ??? for r in row:
> ??????? if s.issubset(r):
> ??????????? pairs[tuple(sorted(s))] += 1
> 
> print(pairs)
> 
> for i in range(9):
> ??? print(pairs[i])
> 
> 

(Repeated/resent from the correct email address.)

-- 
Martin A. Brown
http://linux-ip.net/

From georget22 at brookings.k12.or.us  Tue Nov 16 01:52:53 2021
From: georget22 at brookings.k12.or.us (George Thompson)
Date: Mon, 15 Nov 2021 22:52:53 -0800
Subject: [Tutor] PIP INSTALL face_recognition
Message-ID: <CAFXkK_U56j48QXH5+dbf9EdwkmQjSyAQYOgugL-w6BuPcOjnRw@mail.gmail.com>

When i use the command pip install face_recognition in the command
interface i get this,

C:\WINDOWS\system32>pip install face_recognition
Collecting face_recognition
  Using cached face_recognition-1.3.0-py2.py3-none-any.whl (15 kB)
Collecting dlib>=19.7
  Using cached dlib-19.22.1.tar.gz (7.4 MB)
  Preparing metadata (setup.py) ... done
Requirement already satisfied: Click>=6.0 in
c:\users\ironbeagle\appdata\local\packages\pythonsoftwarefoundation.python.3.9_qbz5n2kfra8p0\localcache\local-packages\python39\site-packages
(from face_recognition) (7.1.2)
Requirement already satisfied: Pillow in
c:\users\ironbeagle\appdata\local\packages\pythonsoftwarefoundation.python.3.9_qbz5n2kfra8p0\localcache\local-packages\python39\site-packages
(from face_recognition) (8.1.0)
Requirement already satisfied: numpy in
c:\users\ironbeagle\appdata\local\packages\pythonsoftwarefoundation.python.3.9_qbz5n2kfra8p0\localcache\local-packages\python39\site-packages
(from face_recognition) (1.21.4)
Requirement already satisfied: face-recognition-models>=0.3.0 in
c:\users\ironbeagle\appdata\local\packages\pythonsoftwarefoundation.python.3.9_qbz5n2kfra8p0\localcache\local-packages\python39\site-packages
(from face_recognition) (0.3.0)
Using legacy 'setup.py install' for dlib, since package 'wheel' is not
installed.
Installing collected packages: dlib, face-recognition
    Running setup.py install for dlib ... error
    ERROR: Command errored out with exit status 1:
     command:
'C:\Users\ironbeagle\AppData\Local\Microsoft\WindowsApps\PythonSoftwareFoundation.Python.3.9_qbz5n2kfra8p0\python.exe'
-u -c 'import io, os, sys, setuptools, tokenize; sys.argv[0] =
'"'"'C:\\Users\\ironbeagle\\AppData\\Local\\Temp\\pip-install-9ilr4sfv\\dlib_6e1e13a836eb4b43848b64834f8aeea9\\setup.py'"'"';
__file__='"'"'C:\\Users\\ironbeagle\\AppData\\Local\\Temp\\pip-install-9ilr4sfv\\dlib_6e1e13a836eb4b43848b64834f8aeea9\\setup.py'"'"';f
= getattr(tokenize, '"'"'open'"'"', open)(__file__) if
os.path.exists(__file__) else io.StringIO('"'"'from setuptools import
setup; setup()'"'"');code = f.read().replace('"'"'\r\n'"'"',
'"'"'\n'"'"');f.close();exec(compile(code, __file__, '"'"'exec'"'"'))'
install --record
'C:\Users\ironbeagle\AppData\Local\Temp\pip-record-lg6p900f\install-record.txt'
--single-version-externally-managed --user --prefix= --compile
--install-headers
'C:\Users\ironbeagle\AppData\Local\Packages\PythonSoftwareFoundation.Python.3.9_qbz5n2kfra8p0\LocalCache\local-packages\Python39\Include\dlib'
         cwd:
C:\Users\ironbeagle\AppData\Local\Temp\pip-install-9ilr4sfv\dlib_6e1e13a836eb4b43848b64834f8aeea9\
    Complete output (8 lines):
    running install
    running build
    running build_py
    package init file 'tools\python\dlib\__init__.py' not found (or not a
regular file)
    running build_ext

    ERROR: CMake must be installed to build dlib

    ----------------------------------------
ERROR: Command errored out with exit status 1:
'C:\Users\ironbeagle\AppData\Local\Microsoft\WindowsApps\PythonSoftwareFoundation.Python.3.9_qbz5n2kfra8p0\python.exe'
-u -c 'import io, os, sys, setuptools, tokenize; sys.argv[0] =
'"'"'C:\\Users\\ironbeagle\\AppData\\Local\\Temp\\pip-install-9ilr4sfv\\dlib_6e1e13a836eb4b43848b64834f8aeea9\\setup.py'"'"';
__file__='"'"'C:\\Users\\ironbeagle\\AppData\\Local\\Temp\\pip-install-9ilr4sfv\\dlib_6e1e13a836eb4b43848b64834f8aeea9\\setup.py'"'"';f
= getattr(tokenize, '"'"'open'"'"', open)(__file__) if
os.path.exists(__file__) else io.StringIO('"'"'from setuptools import
setup; setup()'"'"');code = f.read().replace('"'"'\r\n'"'"',
'"'"'\n'"'"');f.close();exec(compile(code, __file__, '"'"'exec'"'"'))'
install --record
'C:\Users\ironbeagle\AppData\Local\Temp\pip-record-lg6p900f\install-record.txt'
--single-version-externally-managed --user --prefix= --compile
--install-headers
'C:\Users\ironbeagle\AppData\Local\Packages\PythonSoftwareFoundation.Python.3.9_qbz5n2kfra8p0\LocalCache\local-packages\Python39\Include\dlib'
Check the logs for full command output.


Any help?

my program claims no module named "face_recogniiton" and no module names
"cv2"

pip install cv2 give me this,

C:\WINDOWS\system32>pip install cv2
ERROR: Could not find a version that satisfies the requirement cv2 (from
versions: none)
ERROR: No matching distribution found for cv2

Thank you!!

From martin at wonderfrog.net  Tue Nov 16 00:26:46 2021
From: martin at wonderfrog.net (Martin A. Brown)
Date: Mon, 15 Nov 2021 21:26:46 -0800
Subject: [Tutor] A dictionary question
In-Reply-To: <678af609-ee0b-d298-bc6a-ec12bc96ed57@gmail.com>
References: <6aea6665-372a-55b0-a69e-34f10bcb54a4@gmail.com>
 <1faf831f-e2b8-7035-adc2-f59374486166@DancesWithMice.info>
 <deae3f08-ffb2-09b5-77fd-1ce764e6c3cc@gmail.com>
 <c4f68c2a-4144-8cfe-4d0f-ea5b33622950@wichmann.us>
 <678af609-ee0b-d298-bc6a-ec12bc96ed57@gmail.com>
Message-ID: <c32d5e68-e982-f2d1-7e92-2ae780f52916@wonderfrog.net>


Hello Phil,

> Just a quick one while I stop for afternoon tea.
> 
> Using the example provide by Mats, if I print(pairs) I get:
> 
> Counter({(4, 6): 2, (3, 4): 1, (3, 6): 1 etc.
> 
> How would I print the pairs so they look like this:
> 
> (4,6) 2
> (3,4) 1
> (3,6) 1
> 
> My feeble attempt is under the example code. I have looked at a 
> couple of collections tutorials but I cannot relate what I'm 
> seeing to the example below.

The collections.Counter behaves like a dictionary.  Same methods 
should work.  So, try something like these basic loops that take 
advantage of the items() method.

  c = Counter({(4, 6): 2, (3, 4): 1, (3, 6): 1})
  
  # -- loop through all of the key, value items in the dict-like object
  for k, v in c.items(): 
      print( k, v)

  # -- same but only print where the counter for that entry is 2
  for k, v in c.items(): 
      if v == 2: 
          print( k, v) 

Good luck, enjoy the tea (for a change of pace) and leave your 
dictionaries cleaner than when you arrived.  Only you can stop code 
rot!

-Martin

> I'm also wondering how I might do something like this:
> 
> if count == 2:
> 
> ??? do this
> 
> row = [{7,3},{5},{4,6,8},{7,8},{1},{9,3},{7,9},{4,6,3},{2}]
> #row = [{5},{6},{3},{4,7,5},{1,2,4,5},{1,7,5},{1,2,4,7,9},{8},{1,2,4,7,9}]
> 
> set_list = [{1, 2}, {1, 3}, {1, 4}, {1, 5}, {1, 6}, {1, 7}, {1, 8}, {1, 9},
> ??????????? {2, 3}, {2, 4}, {2, 5}, {2, 6}, {2, 7}, {2, 8}, {2, 9},
> ??????????? {3, 4}, {3, 5}, {3, 6}, {3, 7}, {3, 8}, {3, 9},
> ??????????? {4, 5}, {4, 6}, {4, 7}, {4, 8}, {4,9},
> ??????????? {5, 6}, {5, 7}, {5, 8}, {5, 9},
> ??????????? {6, 7}, {6, 8}, {6, 9},
> ??????????? {7, 8}, {7, 9},
> ??????????? {8, 9}
> ??????????? ]
> 
> from collections import Counter
> 
> pairs = Counter()
> 
> for s in set_list:
> ??? for r in row:
> ??????? if s.issubset(r):
> ??????????? pairs[tuple(sorted(s))] += 1
> 
> print(pairs)
> 
> for i in range(9):
> ??? print(pairs[i])
> 
> 

-- 
Martin A. Brown --- Wonderfrog Heavy Industries --- martin at wonderfrog.net

From alan.gauld at yahoo.co.uk  Tue Nov 16 05:49:56 2021
From: alan.gauld at yahoo.co.uk (Alan Gauld)
Date: Tue, 16 Nov 2021 10:49:56 +0000
Subject: [Tutor] PIP INSTALL face_recognition
In-Reply-To: <CAFXkK_U56j48QXH5+dbf9EdwkmQjSyAQYOgugL-w6BuPcOjnRw@mail.gmail.com>
References: <CAFXkK_U56j48QXH5+dbf9EdwkmQjSyAQYOgugL-w6BuPcOjnRw@mail.gmail.com>
Message-ID: <sn02cl$e9b$1@ciao.gmane.io>

On 16/11/2021 06:52, George Thompson wrote:
> When i use the command pip install face_recognition in the command
> interface i get this,

> Installing collected packages: dlib, face-recognition
>     Running setup.py install for dlib ... error
>     ERROR: Command errored out with exit status 1:
>      command:
> 'C:\Users\ironbeagle\AppData\Local\Microsoft\WindowsApps\PythonSoftwareFoundation.Python.3.9_qbz5n2kfra8p0\python.exe'
> -u -c 'import io, os, sys, setuptools, tokenize; sys.argv[0] =
> '"'"'C:\\Users\\ironbeagle\\AppData\\Local\\Temp\\pip-install-9ilr4sfv\\dlib_6e1e13a836eb4b43848b64834f8aeea9\\setup.py'"'"';
> __file__='"'"'C:\\Users\\ironbeagle\\AppData\\Local\\Temp\\pip-install-9ilr4sfv\\dlib_6e1e13a836eb4b43848b64834f8aeea9\\setup.py'"'"';f
> = getattr(tokenize, '"'"'open'"'"', open)(__file__) if
> os.path.exists(__file__) else io.StringIO('"'"'from setuptools import
> setup; setup()'"'"');code = f.read().replace('"'"'\r\n'"'"',
> '"'"'\n'"'"');f.close();exec(compile(code, __file__, '"'"'exec'"'"'))'
> install --record
> 'C:\Users\ironbeagle\AppData\Local\Temp\pip-record-lg6p900f\install-record.txt'
> --single-version-externally-managed --user --prefix= --compile
> --install-headers
> 'C:\Users\ironbeagle\AppData\Local\Packages\PythonSoftwareFoundation.Python.3.9_qbz5n2kfra8p0\LocalCache\local-packages\Python39\Include\dlib'
>          cwd:
> C:\Users\ironbeagle\AppData\Local\Temp\pip-install-9ilr4sfv\dlib_6e1e13a836eb4b43848b64834f8aeea9\
>     Complete output (8 lines):
>     running install
>     running build
>     running build_py
>     package init file 'tools\python\dlib\__init__.py' not found (or not a
> regular file)
>     running build_ext
> 
>     ERROR: CMake must be installed to build dlib


This seems to be the first error.
Do you have cmake installed?

Although that is likely to just trigger more errors because...
this may imply it is going to try to build the package from C
source, do you have a suitable C build environment available?

But I'm no expert in pip and the install tools. I don't use
many 3rd party modules.

-- 
Alan G
Author of the Learn to Program web site
http://www.alan-g.me.uk/
http://www.amazon.com/author/alan_gauld
Follow my photo-blog on Flickr at:
http://www.flickr.com/photos/alangauldphotos



From abba6 at mac.com  Tue Nov 16 05:56:45 2021
From: abba6 at mac.com (=?utf-8?Q?Asbj=C3=B8rn_Bakken?=)
Date: Tue, 16 Nov 2021 11:56:45 +0100
Subject: [Tutor] IDLE
Message-ID: <D20F367C-903C-4EC4-BCDB-E228AA62F940@mac.com>

Hey,

Thanks for all the answers to my problem. I am going to start with 3.10 and follow your advice Alan,

Thank you very much
Asbj?rn Bakken

From gawad at unal.edu.co  Tue Nov 16 07:47:53 2021
From: gawad at unal.edu.co (Gabriel A Awad Aubad)
Date: Tue, 16 Nov 2021 07:47:53 -0500
Subject: [Tutor] Is web scraping allowed?
Message-ID: <CAKLj9qeJ9jVzy99-R0LKiKbBZnx85x_Ev2jmercBK8rbha8CFQ@mail.gmail.com>

Hi everybody!!!

I would like to use The Tutor Archives:
https://mail.python.org/pipermail/tutor/

to give examples of web scraping to my students.

Is web scraping of this repository allowed?

Thanks in advance for your reply.

Best regards,


*Gabriel AWAD*
*Profesor Asociado*
*Departamento de Ciencias de la Computaci?n y de la Decisi?n*
Universidad Nacional de Colombia - Sede Medell?n
Carrera 80 # 65 - 223 Bloque M8A Of. 208
Medell?n, Colombia
C?digo postal: 050041

e-mail: gawad at unal.edu.co
LinkedIn <http://co.linkedin.com/pub/gabriel-awad/9/41a/60>  Twitter
<http://twitter.com/GabrielAWAD>  Facebook
<https://www.facebook.com/gabriel.awad>
Skype: gabriel.awad

*"M?s puede en m? el azar que yo".  *
*                            Miguel de Montaigne*

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Libre
de virus. www.avg.com
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-- 
*Aviso legal:*?El contenido de este mensaje y los archivos adjuntos son 
confidenciales y de uso exclusivo de la Universidad Nacional de Colombia. 
Se encuentran dirigidos s?lo para el uso del destinatario al cual van 
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cualquier persona diferente a este y puede ser ilegal. Si usted lo ha 
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la Universidad.

From manpritsinghece at gmail.com  Tue Nov 16 11:33:36 2021
From: manpritsinghece at gmail.com (Manprit Singh)
Date: Tue, 16 Nov 2021 22:03:36 +0530
Subject: [Tutor] A toy example to have clarity on Sqlite3 module
Message-ID: <CAO1OCwa-_TvFjErr8OSL-vYx=Hsx7RL74C7o6zrxzi-HGXfOGA@mail.gmail.com>

Dear Sir ,

I have written an example of  sqlite 3 module, without using a cursor
object . and with exception handling as given below:

import sqlite3


lang_list = [
    ("Fortran", 1957),
    ("Python", 1991),
    ("Go", 2009),
]

try:
    con = sqlite3.connect("example.db")

    # Create the table
    con.execute("create table lang(name, first_appeared)")

    # Fill the table
    con.executemany("insert into lang values (?, ?)", lang_list)

except sqlite3.OperationalError:   # It can handle if table already exists
    print("Error! You may be trying to make a new table with same name")


else:
   for row in con.execute("select * from lang"):
       print(row)

finally:
    con.close()

This example makes a database example.db, and a table lang.

In try block i have placed the creation of connection object along with the
execute method being called on this connection object to create the table,
then executemany method called on this connection object to insert the
sequence of rows data.
Since an error can occur in all three existing  parts  of the try block, i
have simply put all three in to try block only.

Secondarily here there is a sequence of rows to be inserted, that can only
be done with executemany, this can't be done with execute.

Secondarily - execute , executemany can be called on connection objects
also.

Secondarily I have put OperationalError: with except block that can handle
exception when it is produced due to making a table with same name which is
already existing.

In else block i am printing all the rows of the data.

Secondarily Inside finally block, con.close()  to close the connection at
last

Just need to know, is this the correct implementation ? any suggestions

Regards
Manprit Singh

From wlfraed at ix.netcom.com  Tue Nov 16 15:22:37 2021
From: wlfraed at ix.netcom.com (Dennis Lee Bieber)
Date: Tue, 16 Nov 2021 15:22:37 -0500
Subject: [Tutor] A toy example to have clarity on Sqlite3 module
References: <CAO1OCwa-_TvFjErr8OSL-vYx=Hsx7RL74C7o6zrxzi-HGXfOGA@mail.gmail.com>
Message-ID: <b448pgdsjol5q7ti1nsluefmp9hjplf7kl@4ax.com>

On Tue, 16 Nov 2021 22:03:36 +0530, Manprit Singh
<manpritsinghece at gmail.com> declaimed the following:

>Just need to know, is this the correct implementation ? any suggestions

	If it runs, then it is technically a correct implementation. Is it a
desirable implementation depends on one's environment.

	I believe the ability to do operations directly with the Connection,
without using a Cursor, is an EXTENSION to the DB-API specification. Not
all database connectors may support this type of extension.

	One of the goals of the DB-API specification is to abstract out
differences between actual database engines. In an ideal situation, one
would change the SQLite import to import some other connector module, and
only have to change the call to create the Connection. Things aren't quite
that "ideal", and different connectors use different styles of argument
passing -- which one can query the database (after connecting) to determine
how things are passed, and can programmatically modify the application SQL
syntax to work with that method.

	So, for maximum compatibility, I'd stick with the "create
connection"/"create cursor" (a second reason may be that the extension
version may only be doing "autocommit"; using cursors usually allows for
disabling autocommit and manually grouping a sequence of SQL as a single
transaction, allowing one to rollback the entire group).


-- 
	Wulfraed                 Dennis Lee Bieber         AF6VN
	wlfraed at ix.netcom.com    http://wlfraed.microdiversity.freeddns.org/


From alan.gauld at yahoo.co.uk  Tue Nov 16 17:35:52 2021
From: alan.gauld at yahoo.co.uk (Alan Gauld)
Date: Tue, 16 Nov 2021 22:35:52 +0000
Subject: [Tutor] A toy example to have clarity on Sqlite3 module
In-Reply-To: <CAO1OCwa-_TvFjErr8OSL-vYx=Hsx7RL74C7o6zrxzi-HGXfOGA@mail.gmail.com>
References: <CAO1OCwa-_TvFjErr8OSL-vYx=Hsx7RL74C7o6zrxzi-HGXfOGA@mail.gmail.com>
Message-ID: <sn1bo8$ukr$1@ciao.gmane.io>

On 16/11/2021 16:33, Manprit Singh wrote:
> Dear Sir ,
> 
> I have written an example of  sqlite 3 module, without using a cursor
> object . and with exception handling as given below:
> 

> try:
>     con = sqlite3.connect("example.db")
>     con.execute("create table lang(name, first_appeared)")
>     con.executemany("insert into lang values (?, ?)", lang_list)
> except sqlite3.OperationalError:   # It can handle if table already exists
>     print("Error! You may be trying to make a new table with same name")
> else:
>    for row in con.execute("select * from lang"):
>        print(row)
> finally:
>     con.close()


> Just need to know, is this the correct implementation ? any suggestions

As you say it's a toy example and therefore sufficient for it's purpose.

It is not good database programming style however. You should create
a cursor for anything non-trivial. There are several reasons for
this but one is that if you need to execute multiple different
queries during your app you will need a cursor for each, otherwise
each new query will wipe out the result of the previous one.

If there is not much data being returned you can copy the results
into local variables but on a real-world database that isn't
always practical.

Using "select * from table" is also not recommended since your
code will probably break if the structure of the table is
modified - eg. columns are added. So it is always better
to specify exactly which columns you expect to get back.

Also creating a database table without primary keys (and
usually an ID field) leads to problems in coding (how to
handle duplicates etc)

Using a catch-all try/except is also not usually recommended since
you want to know what part caused the error, so you would need
to introduce code to examine the error in detail.

Closing in a finally clause, however, is good practice. In particular
you should close all open resources including cursors and
connection(s) - there may be more than one!

-- 
Alan G
Author of the Learn to Program web site
http://www.alan-g.me.uk/
http://www.amazon.com/author/alan_gauld
Follow my photo-blog on Flickr at:
http://www.flickr.com/photos/alangauldphotos



From alan.gauld at yahoo.co.uk  Tue Nov 16 17:36:54 2021
From: alan.gauld at yahoo.co.uk (Alan Gauld)
Date: Tue, 16 Nov 2021 22:36:54 +0000
Subject: [Tutor] Is web scraping allowed?
In-Reply-To: <CAKLj9qeJ9jVzy99-R0LKiKbBZnx85x_Ev2jmercBK8rbha8CFQ@mail.gmail.com>
References: <CAKLj9qeJ9jVzy99-R0LKiKbBZnx85x_Ev2jmercBK8rbha8CFQ@mail.gmail.com>
Message-ID: <sn1bq6$ukr$2@ciao.gmane.io>

On 16/11/2021 12:47, Gabriel A Awad Aubad wrote:
> Hi everybody!!!
> 
> I would like to use The Tutor Archives:
> https://mail.python.org/pipermail/tutor/
> 
> to give examples of web scraping to my students.
> 
> Is web scraping of this repository allowed?

You should probably ask on the main Python list, the
devs and site owners are represented there.

-- 
Alan G
Author of the Learn to Program web site
http://www.alan-g.me.uk/
http://www.amazon.com/author/alan_gauld
Follow my photo-blog on Flickr at:
http://www.flickr.com/photos/alangauldphotos



From iken124 at gmail.com  Tue Nov 16 13:11:17 2021
From: iken124 at gmail.com (Ken Lai)
Date: Tue, 16 Nov 2021 10:11:17 -0800
Subject: [Tutor] Verifying password hash is SHA512
Message-ID: <CAHmG26y+4V6nw5w4K2nrpBEUgd=MVGyyky9gvrWC2v09C3qn4A@mail.gmail.com>

Hi All,

I have a program that hashes passwords into SHA512, but I need to confirm.
I found PHP code on the net:

$hashed = hash("sha512", $password);

Does Python have an equivalent?


TIA,

From iken124 at gmail.com  Tue Nov 16 13:13:11 2021
From: iken124 at gmail.com (Ken Lai)
Date: Tue, 16 Nov 2021 10:13:11 -0800
Subject: [Tutor] Verifying password hash is base64
Message-ID: <CAHmG26xp4uZE9mkOENC6V18JF2zSsM0qv6g6X4XYMPSPb38oNg@mail.gmail.com>

Hi All,

I have a program that hashes passwords into base64, but I need to confirm.
I found C# code on the net:

public static bool IsBase64String(this string s)
{
    s = s.Trim();
    return (s.Length % 4 == 0) && Regex.IsMatch(s,
@"^[a-zA-Z0-9\+/]*={0,3}$", RegexOptions.None);

}

Does Python have an equivalent?


TIA,

From alan.gauld at yahoo.co.uk  Tue Nov 16 18:37:37 2021
From: alan.gauld at yahoo.co.uk (Alan Gauld)
Date: Tue, 16 Nov 2021 23:37:37 +0000
Subject: [Tutor] Verifying password hash is base64
In-Reply-To: <CAHmG26xp4uZE9mkOENC6V18JF2zSsM0qv6g6X4XYMPSPb38oNg@mail.gmail.com>
References: <CAHmG26xp4uZE9mkOENC6V18JF2zSsM0qv6g6X4XYMPSPb38oNg@mail.gmail.com>
Message-ID: <sn1fc2$126f$1@ciao.gmane.io>

On 16/11/2021 18:13, Ken Lai wrote:
> Hi All,
> 
> I have a program that hashes passwords into base64, but I need to confirm.
> I found C# code on the net:

> Does Python have an equivalent?

Probably not equivalent but Python does have a base64 module
that should do what you need.


-- 
Alan G
Author of the Learn to Program web site
http://www.alan-g.me.uk/
http://www.amazon.com/author/alan_gauld
Follow my photo-blog on Flickr at:
http://www.flickr.com/photos/alangauldphotos



From alan.gauld at yahoo.co.uk  Tue Nov 16 18:39:27 2021
From: alan.gauld at yahoo.co.uk (Alan Gauld)
Date: Tue, 16 Nov 2021 23:39:27 +0000
Subject: [Tutor] Verifying password hash is SHA512
In-Reply-To: <CAHmG26y+4V6nw5w4K2nrpBEUgd=MVGyyky9gvrWC2v09C3qn4A@mail.gmail.com>
References: <CAHmG26y+4V6nw5w4K2nrpBEUgd=MVGyyky9gvrWC2v09C3qn4A@mail.gmail.com>
Message-ID: <sn1fff$126f$2@ciao.gmane.io>

On 16/11/2021 18:11, Ken Lai wrote:
> Hi All,
> 
> I have a program that hashes passwords into SHA512, but I need to confirm.
> I found PHP code on the net:
> 
> $hashed = hash("sha512", $password);
> 
> Does Python have an equivalent?

Probably not equivalent but it does have the crypt module which
supports SHA512. It might do what you need?


-- 
Alan G
Author of the Learn to Program web site
http://www.alan-g.me.uk/
http://www.amazon.com/author/alan_gauld
Follow my photo-blog on Flickr at:
http://www.flickr.com/photos/alangauldphotos



From manpritsinghece at gmail.com  Tue Nov 16 19:51:51 2021
From: manpritsinghece at gmail.com (Manprit Singh)
Date: Wed, 17 Nov 2021 06:21:51 +0530
Subject: [Tutor] A toy example to have clarity on Sqlite3 module
In-Reply-To: <sn1bo8$ukr$1@ciao.gmane.io>
References: <CAO1OCwa-_TvFjErr8OSL-vYx=Hsx7RL74C7o6zrxzi-HGXfOGA@mail.gmail.com>
 <sn1bo8$ukr$1@ciao.gmane.io>
Message-ID: <CAO1OCwYjQS2Wz4tmmzOP12rBiAN0-hu4UVYMBnOW5c0VvpMG5g@mail.gmail.com>

Dear Sir,
Kindly look at this modified example, need your comments on using
con.rollback() and con.commit() & fetchone(), fetchmany() and fetchall()
import sqlite3


lang_list = [
    ("Fortran", 1957),
    ("Python", 1991),
    ("Go", 2009),
]

try:

    # Connection object represents the database
    con = sqlite3.connect("example.db")

    # Cursor object - To execute the queries & Fetch the records
    cur = con.cursor()

    # Create the table
    cur.execute("create table lang(name, first_appeared)")

    # Fill the table
    cur.executemany("insert into lang values (?, ?)", lang_list)

except sqlite3.Error:  # base class of all exceptions of sqlite3 module

    con.rollback()    # Rolls back any changes to database
    print("Database related error is there")


else:
    con.commit()   # Commits the current transaction
    cur.execute("select name from lang")
    print(cur.fetchone())            # Fetches next row
    print("-------------------")
    print(cur.fetchmany(size=1))     # fetches next rows(size given)
    print("-------------------")
    print(cur.fetchall())            # Fetches all(remaining) rows

finally:
    cur.close()
    con.close()

Placing con.rollback() in the except block will rollback all changes in the
database if any exception occurs, that's why I have placed it in the except
block. con.commit() will commit all changes done so I have placed it in the
else block to ensure if no exception is raised all changes must be
committed..
Need your comments .

Regards
Manprit Singh

On Wed, Nov 17, 2021 at 4:07 AM Alan Gauld via Tutor <tutor at python.org>
wrote:

> On 16/11/2021 16:33, Manprit Singh wrote:
> > Dear Sir ,
> >
> > I have written an example of  sqlite 3 module, without using a cursor
> > object . and with exception handling as given below:
> >
>
> > try:
> >     con = sqlite3.connect("example.db")
> >     con.execute("create table lang(name, first_appeared)")
> >     con.executemany("insert into lang values (?, ?)", lang_list)
> > except sqlite3.OperationalError:   # It can handle if table already
> exists
> >     print("Error! You may be trying to make a new table with same name")
> > else:
> >    for row in con.execute("select * from lang"):
> >        print(row)
> > finally:
> >     con.close()
>
>
> > Just need to know, is this the correct implementation ? any suggestions
>
> As you say it's a toy example and therefore sufficient for it's purpose.
>
> It is not good database programming style however. You should create
> a cursor for anything non-trivial. There are several reasons for
> this but one is that if you need to execute multiple different
> queries during your app you will need a cursor for each, otherwise
> each new query will wipe out the result of the previous one.
>
> If there is not much data being returned you can copy the results
> into local variables but on a real-world database that isn't
> always practical.
>
> Using "select * from table" is also not recommended since your
> code will probably break if the structure of the table is
> modified - eg. columns are added. So it is always better
> to specify exactly which columns you expect to get back.
>
> Also creating a database table without primary keys (and
> usually an ID field) leads to problems in coding (how to
> handle duplicates etc)
>
> Using a catch-all try/except is also not usually recommended since
> you want to know what part caused the error, so you would need
> to introduce code to examine the error in detail.
>
> Closing in a finally clause, however, is good practice. In particular
> you should close all open resources including cursors and
> connection(s) - there may be more than one!
>
> --
> Alan G
> Author of the Learn to Program web site
> http://www.alan-g.me.uk/
> http://www.amazon.com/author/alan_gauld
> Follow my photo-blog on Flickr at:
> http://www.flickr.com/photos/alangauldphotos
>
>
> _______________________________________________
> Tutor maillist  -  Tutor at python.org
> To unsubscribe or change subscription options:
> https://mail.python.org/mailman/listinfo/tutor
>

From mats at wichmann.us  Tue Nov 16 20:20:28 2021
From: mats at wichmann.us (Mats Wichmann)
Date: Tue, 16 Nov 2021 18:20:28 -0700
Subject: [Tutor] Verifying password hash is SHA512
In-Reply-To: <CAHmG26y+4V6nw5w4K2nrpBEUgd=MVGyyky9gvrWC2v09C3qn4A@mail.gmail.com>
References: <CAHmG26y+4V6nw5w4K2nrpBEUgd=MVGyyky9gvrWC2v09C3qn4A@mail.gmail.com>
Message-ID: <dbe33937-cd93-04d0-414c-852644e40836@wichmann.us>

On 11/16/21 11:11, Ken Lai wrote:
> Hi All,
> 
> I have a program that hashes passwords into SHA512, but I need to confirm.
> I found PHP code on the net:
> 
> $hashed = hash("sha512", $password);
> 
> Does Python have an equivalent?

it's not really that clear what you're asking.

In Python, the hashlib module is how you deal with hashes:

https://docs.python.org/3/library/hashlib.html

it supports many different hash formats, many of which are implemented 
behind the covers by a non-Python library.



From manpasco1 at gmail.com  Wed Nov 17 08:51:49 2021
From: manpasco1 at gmail.com (Pascal Maniriho)
Date: Thu, 18 Nov 2021 00:51:49 +1100
Subject: [Tutor] How to remove all empty elements from a list of list
Message-ID: <CA+hU2caq6R0sU+4TT6ufUr+48BRDs7DczKQgHv8xQgpHnEBr-A@mail.gmail.com>

Dear all,

I have the following list in Python and would like to remove all empty
elements without invalidating indices.

mylist = [['write', 'create', 'draw', 'book', 'mkay', '', '', '', '', '',
''], ['hey', 'mykey', 'ange', 'kiki', 'rose', '', '', '', '', '', '', '',
'', '', ''],['name','age','address', 'nationality', '', '', '', '', '', '',
'', '', '', '', '', '']]

I need the output like this:

mylist = [['write', 'create', 'draw', 'book', 'mkay'], ['hey', 'mykey',
'ange', 'kiki', 'rose']]

I have tried to use the following line of code, but it does not give the
expected output.

mylist1 = list(filter(None, mylist))


Kindly help

......

pasco

From alan.gauld at yahoo.co.uk  Wed Nov 17 18:01:57 2021
From: alan.gauld at yahoo.co.uk (Alan Gauld)
Date: Wed, 17 Nov 2021 23:01:57 +0000
Subject: [Tutor] How to remove all empty elements from a list of list
In-Reply-To: <CA+hU2caq6R0sU+4TT6ufUr+48BRDs7DczKQgHv8xQgpHnEBr-A@mail.gmail.com>
References: <CA+hU2caq6R0sU+4TT6ufUr+48BRDs7DczKQgHv8xQgpHnEBr-A@mail.gmail.com>
Message-ID: <sn41l6$m2c$1@ciao.gmane.io>

On 17/11/2021 13:51, Pascal Maniriho wrote:
> Dear all,
> 
> I have the following list in Python and would like to remove all empty
> elements without invalidating indices.

I don;t know what you mean by the last comment.
If you remove elements it must affect the indices,
there is no way to avoid that.

> mylist = [['write', 'create', 'draw', 'book', 'mkay', '', '', '', '', '',
> ''], ['hey', 'mykey', 'ange', 'kiki', 'rose', '', '', '', '', '', '', '',
> '', '', ''],['name','age','address', 'nationality', '', '', '', '', '', '',
> '', '', '', '', '', '']]
> 
> I need the output like this:
> 
> mylist = [['write', 'create', 'draw', 'book', 'mkay'], ['hey', 'mykey',
> 'ange', 'kiki', 'rose']]
> 
> I have tried to use the following line of code, but it does not give the
> expected output.
> 
> mylist1 = list(filter(None, mylist))

First you need to realize that you actually have a list of lists
so you will need a loop. Also to change the embedded lists in
the loop you will need the index which you can get from the
enumerate() function.

Something like:

for index,sublist in mylist:
    mylist[index] = [item for item in sublist if item]

should work.

However, one other query remains. In your example of output you only
have two sublists. Why is the third not included? Is that deliberate?
If so, slicing could remove the last list.

-- 
Alan G
Author of the Learn to Program web site
http://www.alan-g.me.uk/
http://www.amazon.com/author/alan_gauld
Follow my photo-blog on Flickr at:
http://www.flickr.com/photos/alangauldphotos



From mats at wichmann.us  Wed Nov 17 19:21:52 2021
From: mats at wichmann.us (Mats Wichmann)
Date: Wed, 17 Nov 2021 17:21:52 -0700
Subject: [Tutor] How to remove all empty elements from a list of list
In-Reply-To: <CA+hU2caq6R0sU+4TT6ufUr+48BRDs7DczKQgHv8xQgpHnEBr-A@mail.gmail.com>
References: <CA+hU2caq6R0sU+4TT6ufUr+48BRDs7DczKQgHv8xQgpHnEBr-A@mail.gmail.com>
Message-ID: <f1de3631-c16e-6a36-4065-2fb6c4dc91d5@wichmann.us>

On 11/17/21 06:51, Pascal Maniriho wrote:
> Dear all,
> 
> I have the following list in Python and would like to remove all empty
> elements without invalidating indices.
> 
> mylist = [['write', 'create', 'draw', 'book', 'mkay', '', '', '', '', '',
> ''], ['hey', 'mykey', 'ange', 'kiki', 'rose', '', '', '', '', '', '', '',
> '', '', ''],['name','age','address', 'nationality', '', '', '', '', '', '',
> '', '', '', '', '', '']]
> 
> I need the output like this:
> 
> mylist = [['write', 'create', 'draw', 'book', 'mkay'], ['hey', 'mykey',
> 'ange', 'kiki', 'rose']]
> 
> I have tried to use the following line of code, but it does not give the
> expected output.
> 
> mylist1 = list(filter(None, mylist))

It's an interesting problem, and stating it correctly is important as 
far as picking solutions.

There are no empty elements in mylist so from your problem statement 
there is nothing to remove.

There are clearly empty elements in the members of mylist, so you have 
to work a level down (see Alan's reply).

It's often a problem when you try to modify a list while looping over 
it, for which the solution is to loop over a copy so it's safe to delete 
items from the original. But... your try creates a new list anyway, so 
it doesn't seem you have to do modify-in-place (we can't fully guess 
your requirements unless you tell us).

 From the nature of the data, here's a random thought:  this seems to 
have come from somewhere that probably wasn't originally a Python list - 
perhaps processing a text or csv file or some such.  Is it possible it's 
better to strip out trailing blanks - in this example they're all 
trailing, but again, what are the real requirements? - *before* 
converting to a list? That might even be a cleaner way.


From scarletswish11 at gmail.com  Thu Nov 18 12:59:04 2021
From: scarletswish11 at gmail.com (Scar 43)
Date: Thu, 18 Nov 2021 12:59:04 -0500
Subject: [Tutor] (no subject)
Message-ID: <CAEdzRyCAuStVMA6X8Sa6k4_16dTVz2J03u+y1mRNjdy=id6d9w@mail.gmail.com>

Is there a way to get the click coordinates on an HTML image? I'm using
Jupiter notebook, I've seen many ways that track the click coordinates of
downloaded images, but not when you grab the image from a website and
display it in a code cell.

From alan.gauld at yahoo.co.uk  Thu Nov 18 16:28:38 2021
From: alan.gauld at yahoo.co.uk (Alan Gauld)
Date: Thu, 18 Nov 2021 21:28:38 +0000
Subject: [Tutor] (no subject)
In-Reply-To: <CAEdzRyCAuStVMA6X8Sa6k4_16dTVz2J03u+y1mRNjdy=id6d9w@mail.gmail.com>
References: <CAEdzRyCAuStVMA6X8Sa6k4_16dTVz2J03u+y1mRNjdy=id6d9w@mail.gmail.com>
Message-ID: <sn6gia$t7j$1@ciao.gmane.io>

On 18/11/2021 17:59, Scar 43 wrote:
> Is there a way to get the click coordinates on an HTML image? I'm using
> Jupiter notebook, I've seen many ways that track the click coordinates of
> downloaded images, but not when you grab the image from a website and
> display it in a code cell.

I confess that I don't really understand what you mean. What is
the click coordinate? Do you mean the position of the mouse when
it clicks on the image? But that only makes sense in the context
of some kind of app? If its a web app that is processed by the
server. Is that seever your code? If so what framework are you
using CGI? Django? Flask?

I'm also not sure what you mean by a "code cell" - is that a
Jupityr notebook concept?

Maybe if you could describe the use case scenario it would help?
Where is the image, what is clicking on it, how do you expect to
access it? And what environment are you using (eg web framework,
html parsers etc?)

-- 
Alan G
Author of the Learn to Program web site
http://www.alan-g.me.uk/
http://www.amazon.com/author/alan_gauld
Follow my photo-blog on Flickr at:
http://www.flickr.com/photos/alangauldphotos



From phillor9 at gmail.com  Fri Nov 19 00:00:53 2021
From: phillor9 at gmail.com (Phil)
Date: Fri, 19 Nov 2021 16:00:53 +1100
Subject: [Tutor] A dictionary question
In-Reply-To: <3c57b666-6ee-cb21-9bcc-67a4bdb7a545@wonderfrog.net>
References: <6aea6665-372a-55b0-a69e-34f10bcb54a4@gmail.com>
 <1faf831f-e2b8-7035-adc2-f59374486166@DancesWithMice.info>
 <deae3f08-ffb2-09b5-77fd-1ce764e6c3cc@gmail.com>
 <c4f68c2a-4144-8cfe-4d0f-ea5b33622950@wichmann.us>
 <678af609-ee0b-d298-bc6a-ec12bc96ed57@gmail.com>
 <3c57b666-6ee-cb21-9bcc-67a4bdb7a545@wonderfrog.net>
Message-ID: <2b78fb1a-329c-ba8b-e407-bacf7ebc7e1a@gmail.com>


> The collections.Counter behaves like a dictionary.  Same methods
> should work.  So, try something like these basic loops that take
> advantage of the items() method.
>
>    c = Counter({(4, 6): 2, (3, 4): 1, (3, 6): 1})
>    
>    # -- loop through all of the key, value items in the dict-like object
>    for k, v in c.items():
>        print( k, v)
>
>    # -- same but only print where the counter for that entry is 2
>    for k, v in c.items():
>        if v == 2:
>            print( k, v)

Thank you Martin that solved that problem, however, it hasn't help me 
solve the original problem. I've spent a week or more on this and I 
don't seem to be getting anywhere. I'm now wondering if I really need to 
use a dictionary and if I'm really attacking this problem correctly.

The problem is, given a list of sets find a pair of numbers that occur 
in the same row and in no other set in that row.

row = [{7,3},{5},{4,6,8},{7,8},{1},{9,3},{7,9},{4,6,3},{2}]

The pair in this set is {4, 6}. This is an easy one to solve because 
neither the 4 nor the 6 is in any other set. My clumsy code gave me the 
correct answer but it fails if the 4 or the 6 is repeated in another row 
set.

There is no solution for the follow row because there is no unique pair:

row = [{5},{6},{3},{4,7,5},{1,2,4,5},{1,7,5},{1,2,4,7,9},{8},{1,2,4,7,9}]

I just had a bright idea while I'm typing this and the following code 
almost offer a complete solution:

row = [{7,3},{5},{4,6,8},{7,8},{1},{9,3},{7,9},{4,6,3},{2}]

number_list = []
row_list = []

for r in range(9):
 ??? for i in range(1, 10):
 ??????? if i in row[r] and len(row[r]) > 2:
 ??????????? number_list.append(i)
 ??????????? row_list.append(r)

for i in range(len(number_list)):
 ??? print(number_list[i], end=' ')

print()

for i in range(len(row_list)):
 ??? print(row_list[i], end=' ')

At this point I have:

4 6 8 3 4 6
2 2 2 7 7 7

What I need to do now is feed this result into a function that returns 
the? tuple (4, 6). This is just for my own education and is not homework.

I expect to have Internet access the day after tomorrow and in the 
meantime I will see if I can massage this code further towards a solution.

-- 

Regards,
Phil


From alan.gauld at yahoo.co.uk  Fri Nov 19 07:14:46 2021
From: alan.gauld at yahoo.co.uk (Alan Gauld)
Date: Fri, 19 Nov 2021 12:14:46 +0000
Subject: [Tutor] A dictionary question
In-Reply-To: <2b78fb1a-329c-ba8b-e407-bacf7ebc7e1a@gmail.com>
References: <6aea6665-372a-55b0-a69e-34f10bcb54a4@gmail.com>
 <1faf831f-e2b8-7035-adc2-f59374486166@DancesWithMice.info>
 <deae3f08-ffb2-09b5-77fd-1ce764e6c3cc@gmail.com>
 <c4f68c2a-4144-8cfe-4d0f-ea5b33622950@wichmann.us>
 <678af609-ee0b-d298-bc6a-ec12bc96ed57@gmail.com>
 <3c57b666-6ee-cb21-9bcc-67a4bdb7a545@wonderfrog.net>
 <2b78fb1a-329c-ba8b-e407-bacf7ebc7e1a@gmail.com>
Message-ID: <sn84fn$5fe$1@ciao.gmane.io>

On 19/11/2021 05:00, Phil wrote:

> The problem is, given a list of sets find a pair of numbers that occur 
> in the same row and in no other set in that row.
> 
> row = [{7,3},{5},{4,6,8},{7,8},{1},{9,3},{7,9},{4,6,3},{2}]
> 
> The pair in this set is {4, 6}. This is an easy one to solve because 
> neither the 4 nor the 6 is in any other set. 

Your explanation doesn't make sense to me.
row is a list of sets.
Your description says find a pair in the same row(ie same list of sets)
and in no other set in that row(list)
But 4,6 appears in 2 sets within the list?

> correct answer but it fails if the 4 or the 6 is repeated in another row 
> set.

Again I'm not sure what that means. Does it mean repeated in a
different list of sets? or a different (third?) set within
the original row(list)?

> There is no solution for the follow row because there is no unique pair:
> 
> row = [{5},{6},{3},{4,7,5},{1,2,4,5},{1,7,5},{1,2,4,7,9},{8},{1,2,4,7,9}]

Why not 4,5? it appears in 2 sets, which seems to be the criteria?

> I just had a bright idea while I'm typing this and the following code 
> almost offer a complete solution:
> 
> row = [{7,3},{5},{4,6,8},{7,8},{1},{9,3},{7,9},{4,6,3},{2}]
> 
> number_list = []
> row_list = []
> 
> for r in range(9):
>  ??? for i in range(1, 10):
>  ??????? if i in row[r] and len(row[r]) > 2:
>  ??????????? number_list.append(i)
>  ??????????? row_list.append(r)
> 
> for i in range(len(number_list)):
>  ??? print(number_list[i], end=' ')
> 
> print()
> 
> for i in range(len(row_list)):
>  ??? print(row_list[i], end=' ')
> 
> At this point I have:
> 
> 4 6 8 3 4 6
> 2 2 2 7 7 7
> 
> What I need to do now is feed this result into a function that returns 
> the? tuple (4, 6). This is just for my own education and is not homework.

Again you've lost me. Why return 4,6 based on your data.
What makes that the right value?
And which 4,6?
There is a 4,6 pair at both ends of your first row?

Maybe if you can more precisely explain your algorithm and
rules we can provide more specific help.

I seem to recall you saying somewhere that it was a
sudoku puzzle? Is this still part of that?
If so it might help to describe your problem in
terms of the problem domain rather than your current
solution design? What do the sets represent? (cells,
and their guesses so far maybe?)
What are you trying to find within them?

-- 
Alan G
Author of the Learn to Program web site
http://www.alan-g.me.uk/
http://www.amazon.com/author/alan_gauld
Follow my photo-blog on Flickr at:
http://www.flickr.com/photos/alangauldphotos



From mats at wichmann.us  Fri Nov 19 10:09:52 2021
From: mats at wichmann.us (Mats Wichmann)
Date: Fri, 19 Nov 2021 08:09:52 -0700
Subject: [Tutor] A dictionary question
In-Reply-To: <sn84fn$5fe$1@ciao.gmane.io>
References: <6aea6665-372a-55b0-a69e-34f10bcb54a4@gmail.com>
 <1faf831f-e2b8-7035-adc2-f59374486166@DancesWithMice.info>
 <deae3f08-ffb2-09b5-77fd-1ce764e6c3cc@gmail.com>
 <c4f68c2a-4144-8cfe-4d0f-ea5b33622950@wichmann.us>
 <678af609-ee0b-d298-bc6a-ec12bc96ed57@gmail.com>
 <3c57b666-6ee-cb21-9bcc-67a4bdb7a545@wonderfrog.net>
 <2b78fb1a-329c-ba8b-e407-bacf7ebc7e1a@gmail.com> <sn84fn$5fe$1@ciao.gmane.io>
Message-ID: <a1d65139-c0db-cd17-028d-560edaf6759e@wichmann.us>

On 11/19/21 05:14, Alan Gauld via Tutor wrote:

>> There is no solution for the follow row because there is no unique pair:
>>
>> row = [{5},{6},{3},{4,7,5},{1,2,4,5},{1,7,5},{1,2,4,7,9},{8},{1,2,4,7,9}]
> 
> Why not 4,5? it appears in 2 sets, which seems to be the criteria?

because 5 appears by itself in several other sets, as does 4 (that 
second qualifier was not, if I recall, in the original description)

===

and since my partial bit the other day didn't lead to a finished 
solution, I'll repaste it with the second half also included (not 
prettied up):

from collections import Counter

row = [{7,3},{5},{4,8,6},{7,8},{1},{9,3},{7,9},{4,6,3},{2}]
#row = [{5},{6},{3},{4,7,5},{1,2,4,5},{1,7,5},{1,2,4,7,9},{8},{1,2,4,7,9}]

set_list = [{1, 2}, {1, 3}, {1, 4}, {1, 5}, {1, 6}, {1, 7}, {1, 8}, {1, 9},
             {2, 3}, {2, 4}, {2, 5}, {2, 6}, {2, 7}, {2, 8}, {2, 9},
             {3, 4}, {3, 5}, {3, 6}, {3, 7}, {3, 8}, {3, 9},
             {4, 5}, {4, 6}, {4, 7}, {4, 8}, {4,9},
             {5, 6}, {5, 7}, {5, 8}, {5, 9},
             {6, 7}, {6, 8}, {6, 9},
             {7, 8}, {7, 9},
             {8, 9}
             ]

pairs = Counter()

for s in set_list:
     for r in row:
         if s.issubset(r):
             pairs[tuple(sorted(s))] += 1

for item, count in pairs.items():
     if count == 2:  # candidate
         i, j = item
         # since we know we're only counting two things,
         # no need to use a Counter or dict here
         icount, jcount = 0, 0
         for r in row:
             if i in r:
                 icount += 1
             if j in r:
                 jcount += 1
         if icount == 2 and jcount == 2:
             print(f"{set(item)} found")

From breamoreboy at gmail.com  Fri Nov 19 07:29:13 2021
From: breamoreboy at gmail.com (Mark Lawrence)
Date: Fri, 19 Nov 2021 12:29:13 +0000
Subject: [Tutor] A dictionary question
In-Reply-To: <2b78fb1a-329c-ba8b-e407-bacf7ebc7e1a@gmail.com>
References: <6aea6665-372a-55b0-a69e-34f10bcb54a4@gmail.com>
 <1faf831f-e2b8-7035-adc2-f59374486166@DancesWithMice.info>
 <deae3f08-ffb2-09b5-77fd-1ce764e6c3cc@gmail.com>
 <c4f68c2a-4144-8cfe-4d0f-ea5b33622950@wichmann.us>
 <678af609-ee0b-d298-bc6a-ec12bc96ed57@gmail.com>
 <3c57b666-6ee-cb21-9bcc-67a4bdb7a545@wonderfrog.net>
 <2b78fb1a-329c-ba8b-e407-bacf7ebc7e1a@gmail.com>
Message-ID: <9b02095b-1853-7e08-788a-b01793724bc9@gmail.com>

On 19/11/2021 05:00, Phil wrote:

[big snip]

> for r in range(9):
>  ??? for i in range(1, 10):
>  ??????? if i in row[r] and len(row[r]) > 2:
>  ??????????? number_list.append(i)
>  ??????????? row_list.append(r)
> 
> for i in range(len(number_list)):
>  ??? print(number_list[i], end=' ')
> 
> print()
> 
> for i in range(len(row_list)):
>  ??? print(row_list[i], end=' ')
> 

Besides the difficulties of understanding what you actually want, as has 
been raised elsewhere, please start writing standard Python for loops, 
e.g. :-

for row in row_list:
     print(row, end=' ')

If you need the index use 
https://docs.python.org/3/library/functions.html#enumerate

-- 
My fellow Pythonistas, ask not what our language can do for you, ask
what you can do for our language.

Mark Lawrence


From joao.oliveira at ufob.edu.br  Fri Nov 19 12:43:42 2021
From: joao.oliveira at ufob.edu.br (Joao Carlos Silva de Oliveira Matos)
Date: Fri, 19 Nov 2021 14:43:42 -0300
Subject: [Tutor] Getting extra characters when copying CURL from devtools
Message-ID: <CAN8ghrDC3MmYkdZ2hKv7bRQU0K1pqJTuK92T31xwDqH+cQiMCQ@mail.gmail.com>

Since I installed win11 I'm getting extra characters when I copy CURL as
CMD or BASH. It's basically the encoding generating characters like ^ and
line breaks.

I know I can replace them, but I used to just copy it and paste in  Convert
curl commands to code (curlconverter.com) <https://curlconverter.com/> to
translate to Python. And now the website would not recognize this encoding.
Is there any way to select the type of curl encoding when using Devtools?

Oh, and it's happening in Chrome and Edge.


-- 
[image: Ficheiro:Bras?o da UFOB.png ? Wikip?dia, a enciclop?dia livre]
Jo?o Carlos Silva de Oliveira Matos
Bolsista de Inova??o e Tecnologia
PROFNIT - Centro das Humanidades - UFOB
Mat. 2020100150

From alan.gauld at yahoo.co.uk  Fri Nov 19 14:59:39 2021
From: alan.gauld at yahoo.co.uk (Alan Gauld)
Date: Fri, 19 Nov 2021 19:59:39 +0000
Subject: [Tutor] Getting extra characters when copying CURL from devtools
In-Reply-To: <CAN8ghrDC3MmYkdZ2hKv7bRQU0K1pqJTuK92T31xwDqH+cQiMCQ@mail.gmail.com>
References: <CAN8ghrDC3MmYkdZ2hKv7bRQU0K1pqJTuK92T31xwDqH+cQiMCQ@mail.gmail.com>
Message-ID: <sn8vnb$m4u$1@ciao.gmane.io>

On 19/11/2021 17:43, Joao Carlos Silva de Oliveira Matos via Tutor wrote:
> Since I installed win11 I'm getting extra characters when I copy CURL as
> CMD or BASH. It's basically the encoding generating characters like ^ and
> line breaks.
> 
> I know I can replace them, but I used to just copy it and paste in  Convert
> curl commands to code (curlconverter.com) <https://curlconverter.com/> to
> translate to Python. And now the website would not recognize this encoding.
> Is there any way to select the type of curl encoding when using Devtools?

This doesn't really sound like a Python issue, it's all about
your OS and terminal/app combination. There might be somebody here who
uses your tool and might be able to help but its not exactly mainstream.

You might be better asking on curlconvertor, or even a general
curl  forum.

It looks like they have a bug tracker page, try reporting it there.

-- 
Alan G
Author of the Learn to Program web site
http://www.alan-g.me.uk/
http://www.amazon.com/author/alan_gauld
Follow my photo-blog on Flickr at:
http://www.flickr.com/photos/alangauldphotos



From PyTutor at DancesWithMice.info  Fri Nov 19 16:27:20 2021
From: PyTutor at DancesWithMice.info (dn)
Date: Sat, 20 Nov 2021 10:27:20 +1300
Subject: [Tutor] A dictionary question
In-Reply-To: <2b78fb1a-329c-ba8b-e407-bacf7ebc7e1a@gmail.com>
References: <6aea6665-372a-55b0-a69e-34f10bcb54a4@gmail.com>
 <1faf831f-e2b8-7035-adc2-f59374486166@DancesWithMice.info>
 <deae3f08-ffb2-09b5-77fd-1ce764e6c3cc@gmail.com>
 <c4f68c2a-4144-8cfe-4d0f-ea5b33622950@wichmann.us>
 <678af609-ee0b-d298-bc6a-ec12bc96ed57@gmail.com>
 <3c57b666-6ee-cb21-9bcc-67a4bdb7a545@wonderfrog.net>
 <2b78fb1a-329c-ba8b-e407-bacf7ebc7e1a@gmail.com>
Message-ID: <2f61eea8-2cc2-c7b5-3516-559a9b175399@DancesWithMice.info>

On 19/11/2021 18.00, Phil wrote:
> 
>> The collections.Counter behaves like a dictionary.? Same methods
>> should work.? So, try something like these basic loops that take
>> advantage of the items() method.
>>
>> ?? c = Counter({(4, 6): 2, (3, 4): 1, (3, 6): 1})
>> ?? ?? # -- loop through all of the key, value items in the dict-like
>> object
>> ?? for k, v in c.items():
>> ?????? print( k, v)
>>
>> ?? # -- same but only print where the counter for that entry is 2
>> ?? for k, v in c.items():
>> ?????? if v == 2:
>> ?????????? print( k, v)
> 
> Thank you Martin that solved that problem, however, it hasn't help me
> solve the original problem. I've spent a week or more on this and I
> don't seem to be getting anywhere. I'm now wondering if I really need to
> use a dictionary and if I'm really attacking this problem correctly.
> 
> The problem is, given a list of sets find a pair of numbers that occur
> in the same row and in no other set in that row.
> 
> row = [{7,3},{5},{4,6,8},{7,8},{1},{9,3},{7,9},{4,6,3},{2}]
> 
> The pair in this set is {4, 6}. This is an easy one to solve because
> neither the 4 nor the 6 is in any other set. My clumsy code gave me the
> correct answer but it fails if the 4 or the 6 is repeated in another row
> set.
> 
> There is no solution for the follow row because there is no unique pair:
> 
> row = [{5},{6},{3},{4,7,5},{1,2,4,5},{1,7,5},{1,2,4,7,9},{8},{1,2,4,7,9}]
> 
> I just had a bright idea while I'm typing this and the following code
> almost offer a complete solution:
> 
> row = [{7,3},{5},{4,6,8},{7,8},{1},{9,3},{7,9},{4,6,3},{2}]
> 
> number_list = []
> row_list = []
> 
> for r in range(9):
> ??? for i in range(1, 10):
> ??????? if i in row[r] and len(row[r]) > 2:
> ??????????? number_list.append(i)
> ??????????? row_list.append(r)
> 
> for i in range(len(number_list)):
> ??? print(number_list[i], end=' ')
> 
> print()
> 
> for i in range(len(row_list)):
> ??? print(row_list[i], end=' ')
> 
> At this point I have:
> 
> 4 6 8 3 4 6
> 2 2 2 7 7 7
> 
> What I need to do now is feed this result into a function that returns
> the? tuple (4, 6). This is just for my own education and is not homework.


This problem has all the flavor of self-flagellation!

Some relief may be available through "Chapter 8 - Advanced Iterators" of
Mark Pilgrim's (online) book "Dive into Python 3"
(https://diveintopython3.net/index.html).

Whilst not identical, the example used is quite similar, in requiring
pattern-matching techniques across "collections". Thus, 'beg, borrow, or
steal' ideas/algorithms to solve this problem...

Also, you may find the book as an whole, an useful adjunct to whatever
learning-tool currently employed...
-- 
Regards,
=dn

From phillor9 at gmail.com  Fri Nov 19 19:37:44 2021
From: phillor9 at gmail.com (Phil)
Date: Sat, 20 Nov 2021 11:37:44 +1100
Subject: [Tutor] A dictionary question
In-Reply-To: <a1d65139-c0db-cd17-028d-560edaf6759e@wichmann.us>
References: <6aea6665-372a-55b0-a69e-34f10bcb54a4@gmail.com>
 <1faf831f-e2b8-7035-adc2-f59374486166@DancesWithMice.info>
 <deae3f08-ffb2-09b5-77fd-1ce764e6c3cc@gmail.com>
 <c4f68c2a-4144-8cfe-4d0f-ea5b33622950@wichmann.us>
 <678af609-ee0b-d298-bc6a-ec12bc96ed57@gmail.com>
 <3c57b666-6ee-cb21-9bcc-67a4bdb7a545@wonderfrog.net>
 <2b78fb1a-329c-ba8b-e407-bacf7ebc7e1a@gmail.com> <sn84fn$5fe$1@ciao.gmane.io>
 <a1d65139-c0db-cd17-028d-560edaf6759e@wichmann.us>
Message-ID: <c2d0731c-120c-afb6-a4a8-276a4de0ec54@gmail.com>



Thank you Mats. I just arrived at our camping site and I'm amazed that 
there is some mobile phone service here. Once I've settled in I'll run 
through your code to understand how it works.
> pairs = Counter()
>
> for s in set_list:
> ??? for r in row:
> ??????? if s.issubset(r):
> ??????????? pairs[tuple(sorted(s))] += 1
>
> for item, count in pairs.items():
> ??? if count == 2:? # candidate
> ??????? i, j = item
> ??????? # since we know we're only counting two things,
> ??????? # no need to use a Counter or dict here
> ??????? icount, jcount = 0, 0
> ??????? for r in row:
> ??????????? if i in r:
> ??????????????? icount += 1
> ??????????? if j in r:
> ??????????????? jcount += 1
> ??????? if icount == 2 and jcount == 2:
> ??????????? print(f"{set(item)} found")
-- 

Regards,
Phil


From phillor9 at gmail.com  Fri Nov 19 19:40:18 2021
From: phillor9 at gmail.com (Phil)
Date: Sat, 20 Nov 2021 11:40:18 +1100
Subject: [Tutor] A dictionary question
In-Reply-To: <2f61eea8-2cc2-c7b5-3516-559a9b175399@DancesWithMice.info>
References: <6aea6665-372a-55b0-a69e-34f10bcb54a4@gmail.com>
 <1faf831f-e2b8-7035-adc2-f59374486166@DancesWithMice.info>
 <deae3f08-ffb2-09b5-77fd-1ce764e6c3cc@gmail.com>
 <c4f68c2a-4144-8cfe-4d0f-ea5b33622950@wichmann.us>
 <678af609-ee0b-d298-bc6a-ec12bc96ed57@gmail.com>
 <3c57b666-6ee-cb21-9bcc-67a4bdb7a545@wonderfrog.net>
 <2b78fb1a-329c-ba8b-e407-bacf7ebc7e1a@gmail.com>
 <2f61eea8-2cc2-c7b5-3516-559a9b175399@DancesWithMice.info>
Message-ID: <dfb3956d-3e3b-d5f2-bd42-e6c3431191fc@gmail.com>


On 20/11/21 08:27, dn via Tutor wrote:
>
> This problem has all the flavor of self-flagellation!
>
> Some relief may be available through "Chapter 8 - Advanced Iterators" of
> Mark Pilgrim's (online) book "Dive into Python 3"
> (https://diveintopython3.net/index.html).

Thanks dn for the tip, it could be just what I need.

-- 

Regards,
Phil


From phillor9 at gmail.com  Fri Nov 19 19:48:39 2021
From: phillor9 at gmail.com (Phil)
Date: Sat, 20 Nov 2021 11:48:39 +1100
Subject: [Tutor] A dictionary question
In-Reply-To: <9b02095b-1853-7e08-788a-b01793724bc9@gmail.com>
References: <6aea6665-372a-55b0-a69e-34f10bcb54a4@gmail.com>
 <1faf831f-e2b8-7035-adc2-f59374486166@DancesWithMice.info>
 <deae3f08-ffb2-09b5-77fd-1ce764e6c3cc@gmail.com>
 <c4f68c2a-4144-8cfe-4d0f-ea5b33622950@wichmann.us>
 <678af609-ee0b-d298-bc6a-ec12bc96ed57@gmail.com>
 <3c57b666-6ee-cb21-9bcc-67a4bdb7a545@wonderfrog.net>
 <2b78fb1a-329c-ba8b-e407-bacf7ebc7e1a@gmail.com>
 <9b02095b-1853-7e08-788a-b01793724bc9@gmail.com>
Message-ID: <6a0792d5-5431-f931-7a6a-edae0da67fec@gmail.com>


> please start writing standard Python for loops, e.g. :-
>
> for row in row_list:
> ??? print(row, end=' ')

for i in range(len(row_list)):
 ??? print(row_list[i], end=' ')

The result is the same, however, I suppose it does matter and I will try 
to improve.

-- 

Regards,
Phil


From alan.gauld at yahoo.co.uk  Sat Nov 20 04:03:00 2021
From: alan.gauld at yahoo.co.uk (Alan Gauld)
Date: Sat, 20 Nov 2021 09:03:00 +0000
Subject: [Tutor] A dictionary question
In-Reply-To: <6a0792d5-5431-f931-7a6a-edae0da67fec@gmail.com>
References: <6aea6665-372a-55b0-a69e-34f10bcb54a4@gmail.com>
 <1faf831f-e2b8-7035-adc2-f59374486166@DancesWithMice.info>
 <deae3f08-ffb2-09b5-77fd-1ce764e6c3cc@gmail.com>
 <c4f68c2a-4144-8cfe-4d0f-ea5b33622950@wichmann.us>
 <678af609-ee0b-d298-bc6a-ec12bc96ed57@gmail.com>
 <3c57b666-6ee-cb21-9bcc-67a4bdb7a545@wonderfrog.net>
 <2b78fb1a-329c-ba8b-e407-bacf7ebc7e1a@gmail.com>
 <9b02095b-1853-7e08-788a-b01793724bc9@gmail.com>
 <6a0792d5-5431-f931-7a6a-edae0da67fec@gmail.com>
Message-ID: <snadk5$bro$1@ciao.gmane.io>

On 20/11/2021 00:48, Phil wrote:
> 
>> please start writing standard Python for loops, e.g. :-
>>
>> for row in row_list:
>> ??? print(row, end=' ')
> 
> for i in range(len(row_list)):
>  ??? print(row_list[i], end=' ')
> 
> The result is the same, however, I suppose it does matter 

The code is easier to read and more reliable, easier to maintain.
(It's less liable to index errors) It's also more Pythonic so
other Python programmers (and probably even you in 6 months
time) will understand it faster.

But it also makes a difference to performance since using
indexes Python has to do a lot of extra work finding the
element each time it's accessed. So, although you won't notice
the difference in 99% of normal code if you are trying to
do something performance intensive or on very large lists
it will make a difference.

Finally, there is the matter of credibility. Posting code
like this will immediately mark you out as a beginner in
the eyes of experienced python coders and so they will
tend to respond to any questions on that basis. They won't
be deliberately patronising but it will just be an automatic
assumption if they see an indexed for loop.

-- 
Alan G
Author of the Learn to Program web site
http://www.alan-g.me.uk/
http://www.amazon.com/author/alan_gauld
Follow my photo-blog on Flickr at:
http://www.flickr.com/photos/alangauldphotos



From archinagaraj at gmail.com  Fri Nov 19 16:51:54 2021
From: archinagaraj at gmail.com (Nagaraj S)
Date: Sat, 20 Nov 2021 03:21:54 +0530
Subject: [Tutor] Principles of code reuse error (Nagaraj S)
Message-ID: <CADCKVkj31LEP8-_V0f7L+ehN0z6XsmaoQngpFhAM1HtxAZwj=w@mail.gmail.com>

HI
Can you please help me with this?

Below is the question, answer and the result error I received.


In this code, identify the repeated pattern and replace it with a function
called month_days, that receives the name of the *month *and the number of
*days* in that month as parameters. Adapt the rest of the code so that the
result is the same. Confirm your results by making a function call with the
correct parameters for both months listed.

def month_days(month, days):
   print(month +" has " + days +" days")
month_days("june", "30")
month_days("july", "31")

Here is your output:
june has 30 days
july has 31 days

Not quite. Let your function do most of the work and just
pass the name of the month and the associated days as
parameters.

From manpritsinghece at gmail.com  Sat Nov 20 06:52:08 2021
From: manpritsinghece at gmail.com (Manprit Singh)
Date: Sat, 20 Nov 2021 17:22:08 +0530
Subject: [Tutor] Appropriate use of assignment expression
Message-ID: <CAO1OCwbG+_DwVt=HStycM_xZx+1x1bsXHqyxemj_XnB9KNzerw@mail.gmail.com>

Dear sir,

Consider a problem of list of numbers as given below :

ls = [234, 5445, 613, 959, 3441, 212, 239]

Now i only need those numbers from the list ls which are palindrome, into a
new list, doing this way gives the result :

ans = [ele for ele in ls if (y:=str(ele))==y[::-1]]
print(ans)    # Gives result given below which is the right answer
[5445, 959, 212]

Is it ok to use assignment expressions in this way ?

Regards
Manprit Singh

From alan.gauld at yahoo.co.uk  Sat Nov 20 09:03:18 2021
From: alan.gauld at yahoo.co.uk (Alan Gauld)
Date: Sat, 20 Nov 2021 14:03:18 +0000
Subject: [Tutor] Appropriate use of assignment expression
In-Reply-To: <CAO1OCwbG+_DwVt=HStycM_xZx+1x1bsXHqyxemj_XnB9KNzerw@mail.gmail.com>
References: <CAO1OCwbG+_DwVt=HStycM_xZx+1x1bsXHqyxemj_XnB9KNzerw@mail.gmail.com>
Message-ID: <snav76$nro$1@ciao.gmane.io>

On 20/11/2021 11:52, Manprit Singh wrote:
> Dear sir,
> 
> Consider a problem of list of numbers as given below :
> 
> ls = [234, 5445, 613, 959, 3441, 212, 239]
> 
> Now i only need those numbers from the list ls which are palindrome, into a
> new list, doing this way gives the result :
> 
> ans = [ele for ele in ls if (y:=str(ele))==y[::-1]]
> print(ans)    # Gives result given below which is the right answer
> [5445, 959, 212]
> 
> Is it ok to use assignment expressions in this way ?

If it works it must be OK.

There has been a lot of debate just recently on the main
Python list about how and when you should use the new
"walrus" operator. But it is so new there has not been
time for a community consensus to form over the best
practice. So for now, if it works, you can use it.

Personally, I've been burned so many times with assignments
inside tests in C that I try my best to avoid it if at all
possible. (I have found occasional cases where it just
makes things so much simpler that it's foolish not to - this
example may even be such a case!

-- 
Alan G
Author of the Learn to Program web site
http://www.alan-g.me.uk/
http://www.amazon.com/author/alan_gauld
Follow my photo-blog on Flickr at:
http://www.flickr.com/photos/alangauldphotos



From alan.gauld at yahoo.co.uk  Sat Nov 20 09:11:59 2021
From: alan.gauld at yahoo.co.uk (Alan Gauld)
Date: Sat, 20 Nov 2021 14:11:59 +0000
Subject: [Tutor] Principles of code reuse error (Nagaraj S)
In-Reply-To: <CADCKVkj31LEP8-_V0f7L+ehN0z6XsmaoQngpFhAM1HtxAZwj=w@mail.gmail.com>
References: <CADCKVkj31LEP8-_V0f7L+ehN0z6XsmaoQngpFhAM1HtxAZwj=w@mail.gmail.com>
Message-ID: <snavnf$qem$1@ciao.gmane.io>

On 19/11/2021 21:51, Nagaraj S wrote:

> In this code, identify the repeated pattern and replace it with a function

You didn't show us the original code so the error might be something
beyond the parameter types.

> *days* in that month as parameters. Adapt the rest of the code so that the
> result is the same. 

Without seeing the code we can't tell what the original "result"
might have been.

> Confirm your results by making a function call with the
> correct parameters for both months listed.
> 
> def month_days(month, days):
>    print(month +" has " + days +" days")

Given the subject line I feel bound to point out that for reuse
your function should not print() the result but return it as
a string. This will make your function reusable in other
contexts such as a web page or GUI application. The current
version only works in a command line environment.

That change would then require you to print() the result
of the function in the main body of your code.

-- 
Alan G
Author of the Learn to Program web site
http://www.alan-g.me.uk/
http://www.amazon.com/author/alan_gauld
Follow my photo-blog on Flickr at:
http://www.flickr.com/photos/alangauldphotos



From Richard at Damon-Family.org  Sat Nov 20 09:33:53 2021
From: Richard at Damon-Family.org (Richard Damon)
Date: Sat, 20 Nov 2021 09:33:53 -0500
Subject: [Tutor] Appropriate use of assignment expression
In-Reply-To: <snav76$nro$1@ciao.gmane.io>
References: <CAO1OCwbG+_DwVt=HStycM_xZx+1x1bsXHqyxemj_XnB9KNzerw@mail.gmail.com>
 <snav76$nro$1@ciao.gmane.io>
Message-ID: <e4d1f904-3a24-a9d8-55bc-c4053af57b6e@Damon-Family.org>

On 11/20/21 9:03 AM, Alan Gauld via Tutor wrote:
> On 20/11/2021 11:52, Manprit Singh wrote:
>> Dear sir,
>>
>> Consider a problem of list of numbers as given below :
>>
>> ls = [234, 5445, 613, 959, 3441, 212, 239]
>>
>> Now i only need those numbers from the list ls which are palindrome, into a
>> new list, doing this way gives the result :
>>
>> ans = [ele for ele in ls if (y:=str(ele))==y[::-1]]
>> print(ans)    # Gives result given below which is the right answer
>> [5445, 959, 212]
>>
>> Is it ok to use assignment expressions in this way ?
> If it works it must be OK.
>
> There has been a lot of debate just recently on the main
> Python list about how and when you should use the new
> "walrus" operator. But it is so new there has not been
> time for a community consensus to form over the best
> practice. So for now, if it works, you can use it.
>
> Personally, I've been burned so many times with assignments
> inside tests in C that I try my best to avoid it if at all
> possible. (I have found occasional cases where it just
> makes things so much simpler that it's foolish not to - this
> example may even be such a case!
>
One BIG thing to point out is that C leaves a lot of details about the 
order things happen to up to the implementation, so this sort of 
statement might not work there.

Python defines the order much more strictly, so we KNOW that y will be 
set to str(ele) before we reverse it with y[::-1] so we have the needed 
promises to be able to say that it will 'work'.

In this case, the question seems to not really be 'Does it work' but is 
it 'good' in the sense of being readable, and that question doesn't 
always have a clean answer, as like many things, it depends.

Personally, I tend to like to decompose into clearly defined functions 
so I might create as is_palindrome function which takes a string and 
returns a bool that it true for a palindrome input string. That gives a 
LONGER program, and maybe a bit slower (due to the added call) but one 
easier to mentally parse, and thus one I would feel more confident that 
it will work.

-- 
Richard Damon


From alan.gauld at yahoo.co.uk  Sat Nov 20 12:01:07 2021
From: alan.gauld at yahoo.co.uk (Alan Gauld)
Date: Sat, 20 Nov 2021 17:01:07 +0000
Subject: [Tutor] Appropriate use of assignment expression
In-Reply-To: <e4d1f904-3a24-a9d8-55bc-c4053af57b6e@Damon-Family.org>
References: <CAO1OCwbG+_DwVt=HStycM_xZx+1x1bsXHqyxemj_XnB9KNzerw@mail.gmail.com>
 <snav76$nro$1@ciao.gmane.io>
 <e4d1f904-3a24-a9d8-55bc-c4053af57b6e@Damon-Family.org>
Message-ID: <snb9kk$pc8$1@ciao.gmane.io>

On 20/11/2021 14:33, Richard Damon wrote:

>> Personally, I've been burned so many times with assignments
>> inside tests in C that I try my best to avoid it 

> One BIG thing to point out is that C leaves a lot of details about the 
> order things happen to up to the implementation, so this sort of 
> statement might not work there.

To be honest there are many features of Python and its
implementation of the walrus assignment that are tighter
than C so my fears are not really justified, it's just
painful experience making me wary. (And to be fair C++
has tightened up many of C's shortcomings in those
areas too)

> Personally, I tend to like to decompose into clearly defined functions 

Exactly, and that's what I tend to do in places where
many might use the walrus. It's more expressive, easier
to debug and extend.

The walrus is one of those 'nice to have' things that is
mainly used by those who think there are prizes for
writing the shortest code. It's just not true.

-- 
Alan G
Author of the Learn to Program web site
http://www.alan-g.me.uk/
http://www.amazon.com/author/alan_gauld
Follow my photo-blog on Flickr at:
http://www.flickr.com/photos/alangauldphotos



From wlfraed at ix.netcom.com  Sat Nov 20 12:45:34 2021
From: wlfraed at ix.netcom.com (Dennis Lee Bieber)
Date: Sat, 20 Nov 2021 12:45:34 -0500
Subject: [Tutor] Principles of code reuse error (Nagaraj S)
References: <CADCKVkj31LEP8-_V0f7L+ehN0z6XsmaoQngpFhAM1HtxAZwj=w@mail.gmail.com>
Message-ID: <hicipgdahrbge7untom8sqsr3fnbhr5645@4ax.com>

On Sat, 20 Nov 2021 03:21:54 +0530, Nagaraj S <archinagaraj at gmail.com>
declaimed the following:

>
>Below is the question, answer and the result error I received.
>
>
>In this code, identify the repeated pattern and replace it with a function

	You have failed to show US "this code". We have no idea what the
"repeated pattern" might be.

>called month_days, that receives the name of the *month *and the number of
>*days* in that month as parameters. Adapt the rest of the code so that the
>result is the same. Confirm your results by making a function call with the
>correct parameters for both months listed.
>
>def month_days(month, days):
>   print(month +" has " + days +" days")

	It's been mentioned that you may need to return the result rather than
directly print it...

>month_days("june", "30")
>month_days("july", "31")
>
	You are passing the NUMBER of days as STRINGs, not numbers.

>Here is your output:
>june has 30 days
>july has 31 days
>
>Not quite. Let your function do most of the work and just
>pass the name of the month and the associated days as
>parameters.


	Again, seeing the "original" code may be required. Technically, you are
passing the month name, and (as string) the days in the month. Though
personally, I'd consider this function to be error-prone -- consider: 
	month_days("February", "32").
The function requires the caller to KNOW the days in the month, and is just
formatting them for output.

	I'd have expected some example where one provides the name of the
month, and the function /returns/ the days in that month.
>_______________________________________________
>Tutor maillist  -  Tutor at python.org
>To unsubscribe or change subscription options:
>https://mail.python.org/mailman/listinfo/tutor


-- 
	Wulfraed                 Dennis Lee Bieber         AF6VN
	wlfraed at ix.netcom.com    http://wlfraed.microdiversity.freeddns.org/


From wlfraed at ix.netcom.com  Sat Nov 20 13:07:26 2021
From: wlfraed at ix.netcom.com (Dennis Lee Bieber)
Date: Sat, 20 Nov 2021 13:07:26 -0500
Subject: [Tutor] Appropriate use of assignment expression
References: <CAO1OCwbG+_DwVt=HStycM_xZx+1x1bsXHqyxemj_XnB9KNzerw@mail.gmail.com>
Message-ID: <gddipghp1rbbi11pjd2jots6kk1dpp8mrp@4ax.com>

On Sat, 20 Nov 2021 17:22:08 +0530, Manprit Singh
<manpritsinghece at gmail.com> declaimed the following:

>Consider a problem of list of numbers as given below :
>
>ls = [234, 5445, 613, 959, 3441, 212, 239]
>
>Now i only need those numbers from the list ls which are palindrome, into a
>new list, doing this way gives the result :
>
>ans = [ele for ele in ls if (y:=str(ele))==y[::-1]]
>print(ans)    # Gives result given below which is the right answer
>[5445, 959, 212]
>
>Is it ok to use assignment expressions in this way ?
>

	And once again, you are really asking about STYLE -- if the code
produces the result you want, it is not wrong. But would a corporate
environment accept this? They may have style guides.

	I'd consider

			... str(ele) == str(ele)[::-1]

to be more legible in most constructs. But since even the [::-1] may be
confusing to those not familiar with some features of slicing, I'm really
more likely to use

			... str(ele) == "".join(reversed(str(ele)))

as it is more explicit about what is being compared. 

	An "assignment expression" would make more sense IF the name that
receives the result is used in later statements. Compare

	if not (errcode := somefunction(...)):
		#no error, continue processing
	else:
		#assumes non-zero is an error
		if errcode = 1:
			#do something
		elsif errcode = 2:
			#do something else
		else:
			#do something for all other error codes

vs

	errcode = somefunction(...)
	if not errcode:
		#no error, continue processing
	else:
		#assumes non-zero is an error
		if errcode = 1:
			#do something
		elsif errcode = 2:
			#do something else
		else:
			#do something for all other error codes


-- 
	Wulfraed                 Dennis Lee Bieber         AF6VN
	wlfraed at ix.netcom.com    http://wlfraed.microdiversity.freeddns.org/


From PyTutor at DancesWithMice.info  Sat Nov 20 15:05:28 2021
From: PyTutor at DancesWithMice.info (dn)
Date: Sun, 21 Nov 2021 09:05:28 +1300
Subject: [Tutor] Appropriate use of assignment expression
In-Reply-To: <snb9kk$pc8$1@ciao.gmane.io>
References: <CAO1OCwbG+_DwVt=HStycM_xZx+1x1bsXHqyxemj_XnB9KNzerw@mail.gmail.com>
 <snav76$nro$1@ciao.gmane.io>
 <e4d1f904-3a24-a9d8-55bc-c4053af57b6e@Damon-Family.org>
 <snb9kk$pc8$1@ciao.gmane.io>
Message-ID: <767aa7db-4819-b666-19e9-46933f754616@DancesWithMice.info>

On 21/11/2021 06.01, Alan Gauld via Tutor wrote:
> On 20/11/2021 14:33, Richard Damon wrote:
> 
>>> Personally, I've been burned so many times with assignments
>>> inside tests in C that I try my best to avoid it 
> 
>> One BIG thing to point out is that C leaves a lot of details about the 
>> order things happen to up to the implementation, so this sort of 
>> statement might not work there.
> 
> To be honest there are many features of Python and its
> implementation of the walrus assignment that are tighter
> than C so my fears are not really justified, it's just
> painful experience making me wary. (And to be fair C++
> has tightened up many of C's shortcomings in those
> areas too)
> 
>> Personally, I tend to like to decompose into clearly defined functions 
> 
> Exactly, and that's what I tend to do in places where
> many might use the walrus. It's more expressive, easier
> to debug and extend.
> 
> The walrus is one of those 'nice to have' things that is
> mainly used by those who think there are prizes for
> writing the shortest code. It's just not true.


There are some situations where the Walrus is invaluable. The 'top' of a
while-loop with some sort of incremental-control may be one. I coded an
assignment-expression yesterday, and was almost sad when refactoring
suggested 'a better way' that saw it removed. (sigh)


However, whilst some may regard 'short' as 'elegant', the earlier
(posts) comments about readability are inescapable.

On which theme, such comment applies equally to the list-comprehension
component of the construction (and other comprehensions generally).

All of the above criticisms are confirmed by the Python interpreter. In
the sense that if there is a problem, it will flag the entire line.
Beyond simple syntax failings, it is no more able to guide you to the
actual clause at-issue, than a human reader! Is it the assignment, the
for, the if, the slice, or the walrus?


As a gentle guide, many would suggest that learners 'construct'
one-liners in their 'full-fat code' version first. In which case, both
Python and a debugger will be more helpful and less frustrating (when
needed). Also, once the construct is tested/proven, one can?should then
ask the question: what do I gain by condensing (part of) this?


Yes, a more skilled pythonista might be able to 'think in
comprehensions' and that is fine for him/her. Whither the rest of the team?

People sometimes talk of 'code-smells' - eg certain constructions which
indicate a coder's lack of Python-technique, or a failure to appreciate
the use of a recognised (and time-tested) pattern. There is a similar
warning sign when a unit of code fails its tests, for some non-trivial
reason, and the author stubbornly refuses to 'unwind' a one-liner! Ego
vs efficacy? Even with complete cooperation, if that is in-fact the
source of the fault, one has to then ask (again): what did I (really)
gain by condensing this?


(counter-argument: yes there are applications where minute
performance-gains are necessary, and thus such skills, valuable)
-- 
Regards,
=dn

From leamhall at gmail.com  Sat Nov 20 16:05:19 2021
From: leamhall at gmail.com (Leam Hall)
Date: Sat, 20 Nov 2021 15:05:19 -0600
Subject: [Tutor] Appropriate use of assignment expression
In-Reply-To: <767aa7db-4819-b666-19e9-46933f754616@DancesWithMice.info>
References: <CAO1OCwbG+_DwVt=HStycM_xZx+1x1bsXHqyxemj_XnB9KNzerw@mail.gmail.com>
 <snav76$nro$1@ciao.gmane.io>
 <e4d1f904-3a24-a9d8-55bc-c4053af57b6e@Damon-Family.org>
 <snb9kk$pc8$1@ciao.gmane.io>
 <767aa7db-4819-b666-19e9-46933f754616@DancesWithMice.info>
Message-ID: <b0254a4c-08f6-52c7-8fee-20db22aa2ffb@gmail.com>

On 11/20/21 14:05, dn via Tutor wrote:

> As a gentle guide, many would suggest that learners 'construct'
> one-liners in their 'full-fat code' version first. 

And you can build your tests much more easily when your mind easily understands the code. I find myself doing a very small bit at a time and running the tests. Often, taking a slow and methodical approach helps me see places where a method can be extracted and the code be even cleaner.

> (counter-argument: yes there are applications where minute
> performance-gains are necessary, and thus such skills, valuable)

At which point I would ask, is Python the right tool for the task? In general, Python seems able to do a lot of things "fast enough" for most of us. If you really need faster you can drop in some C code or re-write in Go or Rust.

Leam

-- 
Systems Programmer         (reuel.net/resume)
Scribe: The Domici War     (domiciwar.net)
General Ne'er-do-well      (github.com/LeamHall)

From phillor9 at gmail.com  Sat Nov 20 19:10:37 2021
From: phillor9 at gmail.com (Phil)
Date: Sun, 21 Nov 2021 11:10:37 +1100
Subject: [Tutor] A dictionary question
In-Reply-To: <snadk5$bro$1@ciao.gmane.io>
References: <6aea6665-372a-55b0-a69e-34f10bcb54a4@gmail.com>
 <1faf831f-e2b8-7035-adc2-f59374486166@DancesWithMice.info>
 <deae3f08-ffb2-09b5-77fd-1ce764e6c3cc@gmail.com>
 <c4f68c2a-4144-8cfe-4d0f-ea5b33622950@wichmann.us>
 <678af609-ee0b-d298-bc6a-ec12bc96ed57@gmail.com>
 <3c57b666-6ee-cb21-9bcc-67a4bdb7a545@wonderfrog.net>
 <2b78fb1a-329c-ba8b-e407-bacf7ebc7e1a@gmail.com>
 <9b02095b-1853-7e08-788a-b01793724bc9@gmail.com>
 <6a0792d5-5431-f931-7a6a-edae0da67fec@gmail.com> <snadk5$bro$1@ciao.gmane.io>
Message-ID: <a0e50a95-eb2f-cf4c-862f-1e5a426860d0@gmail.com>


On 20/11/21 20:03, Alan Gauld via Tutor wrote:
>
> The code is easier to read and more reliable, easier to maintain.
> (It's less liable to index errors) It's also more Pythonic so
> other Python programmers (and probably even you in 6 months
> time) will understand it faster.

OK Alan, understood.

Just one thing though, a snippet from the code that Mats generously gave me.

for r in row:
 ??? if i in r:
 ??? ??? icount += 1

I need the set position within the row list so I did this:

for r in range(num_rows):

 ??? if i in row[i]:
 ??? ??? icount += 1
 ?? ?? ? irow = row[i]

Is this a task for enumerate? A brief test showed this not to be the 
case but I will experiment some more.

-- 

Regards,
Phil


From tcm2118 at columbia.edu  Sat Nov 20 12:14:36 2021
From: tcm2118 at columbia.edu (Tristin Cara Moone)
Date: Sat, 20 Nov 2021 12:14:36 -0500
Subject: [Tutor] Appropriate use of assignment expression
In-Reply-To: <snb9kk$pc8$1@ciao.gmane.io>
References: <CAO1OCwbG+_DwVt=HStycM_xZx+1x1bsXHqyxemj_XnB9KNzerw@mail.gmail.com>
 <snav76$nro$1@ciao.gmane.io>
 <e4d1f904-3a24-a9d8-55bc-c4053af57b6e@Damon-Family.org>
 <snb9kk$pc8$1@ciao.gmane.io>
Message-ID: <CALbiLoddSyotij6RYARaMLmSGr_YdAMqZLf0yp_sjOs+7=jyYw@mail.gmail.com>

On Sat, Nov 20, 2021 at 12:04 PM Alan Gauld via Tutor <tutor at python.org>
wrote:

> On 20/11/2021 14:33, Richard Damon wrote:
>
> >> Personally, I've been burned so many times with assignments
> >> inside tests in C that I try my best to avoid it
>
> > One BIG thing to point out is that C leaves a lot of details about the
> > order things happen to up to the implementation, so this sort of
> > statement might not work there.
>
> To be honest there are many features of Python and its
> implementation of the walrus assignment that are tighter
> than C so my fears are not really justified, it's just
> painful experience making me wary. (And to be fair C++
> has tightened up many of C's shortcomings in those
> areas too)
>
> > Personally, I tend to like to decompose into clearly defined functions
>
> Exactly, and that's what I tend to do in places where
> many might use the walrus. It's more expressive, easier
> to debug and extend.
>
> The walrus is one of those 'nice to have' things that is
> mainly used by those who think there are prizes for
> writing the shortest code. It's just not true.
>
> --
> Alan G
> Author of the Learn to Program web site
> http://www.alan-g.me.uk/
> http://www.amazon.com/author/alan_gauld
> Follow my photo-blog on Flickr at:
> http://www.flickr.com/photos/alangauldphotos
>
>
> _______________________________________________
> Tutor maillist  -  Tutor at python.org
> To unsubscribe or change subscription options:
> https://mail.python.org/mailman/listinfo/tutor
>


-- 
Thank you.

From phillor9 at gmail.com  Sat Nov 20 20:21:39 2021
From: phillor9 at gmail.com (Phil)
Date: Sun, 21 Nov 2021 12:21:39 +1100
Subject: [Tutor] A dictionary question
In-Reply-To: <snadk5$bro$1@ciao.gmane.io>
References: <6aea6665-372a-55b0-a69e-34f10bcb54a4@gmail.com>
 <1faf831f-e2b8-7035-adc2-f59374486166@DancesWithMice.info>
 <deae3f08-ffb2-09b5-77fd-1ce764e6c3cc@gmail.com>
 <c4f68c2a-4144-8cfe-4d0f-ea5b33622950@wichmann.us>
 <678af609-ee0b-d298-bc6a-ec12bc96ed57@gmail.com>
 <3c57b666-6ee-cb21-9bcc-67a4bdb7a545@wonderfrog.net>
 <2b78fb1a-329c-ba8b-e407-bacf7ebc7e1a@gmail.com>
 <9b02095b-1853-7e08-788a-b01793724bc9@gmail.com>
 <6a0792d5-5431-f931-7a6a-edae0da67fec@gmail.com> <snadk5$bro$1@ciao.gmane.io>
Message-ID: <2234fdcb-4969-df6b-5f1c-355017d51f65@gmail.com>

Please ignore my previous message regarding enumerate, problem solved.

-- 

Regards,
Phil


From phillor9 at gmail.com  Sun Nov 21 19:13:15 2021
From: phillor9 at gmail.com (Phil)
Date: Mon, 22 Nov 2021 11:13:15 +1100
Subject: [Tutor] The Python way and two dimensional lists
Message-ID: <dd686338-48ea-8114-190f-c9dc0a185073@gmail.com>

I hope my questions are not becoming too tiresome.

It will require a major effort to rewrite my use of lists in the Python 
way and so I want to make sure that the first steps are correct. The 
first index refers to the columns and the second to the rows.

num_rows = 9
num_cols = 9

solution = [[0 for i in range(num_cols)] for j in range(num_rows)]

solution[0][0] = {7,3}
solution[1][0] = {5}
solution[2][0] = {4,8,6}
solution[3][0] = {7,8}
solution[4][0] = {1}
solution[5][0] = {9,3}
solution[6][0] = {7,9}
solution[7][0] = {4,6,3}
solution[8][0] = {2}

solution[0][1] = {1,2,3}

#print(solution)

for col in solution:
 ??? print(col[0])

print()

for row in solution:
 ??? print(row[1])

If I want to refer to column 6, is it the Python way to say x = col[6]?

Also regarding enumeration. The following is a slight modification to 
Mats code and it gives me exactly what I want:

row = [{7,3},{5},{4,8,6},{7,8},{1},{9,3},{7,9},{4,6,3},{2}]

enum_row = enumerate(row)
row_position = []

for index, enum_row in enumerate(row):
 ??? print('enum_row ',enum_row )
 ??? ??? if i in enum_row:#r:
 ??????? ??? icount += 1
 ??????????? row_position.append(index)

Now returning to the two dimensional list above and assuming that col[0] 
is referring to a row (just for this question only). I'm not sure if 
this is correct because of an error in another section of the code

enum_row = enumerate(col[0]) # instead or row

for index, enum_row in enumerate(col[0]): # instead or row
 ??? print('enum_row ',enum_row )
 ??? ??? if i in enum_row:
 ??????? ??? icount += 1

This is where the error is occurring (also from Mats code):

for s in set_list:
 ??? for r in col[0]: # instead of row:
 ??????? if s.issubset(r):
 ??????????? pairs[tuple(sorted(s))] += 1

Traceback (most recent call last):
 ? File "/usr/lib/python3.9/idlelib/run.py", line 559, in runcode
 ??? exec(code, self.locals)
 ? File "/home/phil/Python/set_count2.py", line 75, in <module>
 ??? if s.issubset(r):
TypeError: 'int' object is not iterable

Confusion is setting in. I think my use of enumerate is correct and I 
think the way that I'm referencing a row from the solution list is 
correct. If both of those aren't the source of the error then it has to 
do with my use of sets. for r in col[0] doesn't give me the sets 
{7,3},{5} etc.

Searching the Internet for information hasn't made me any wiser yet and 
again I'm sorry to burden the list members with my problems.

-- 
Regards,
Phil


From alan.gauld at yahoo.co.uk  Sun Nov 21 19:55:20 2021
From: alan.gauld at yahoo.co.uk (Alan Gauld)
Date: Mon, 22 Nov 2021 00:55:20 +0000
Subject: [Tutor] The Python way and two dimensional lists
In-Reply-To: <dd686338-48ea-8114-190f-c9dc0a185073@gmail.com>
References: <dd686338-48ea-8114-190f-c9dc0a185073@gmail.com>
Message-ID: <sneppr$ifj$1@ciao.gmane.io>

On 22/11/2021 00:13, Phil wrote:
> I hope my questions are not becoming too tiresome.

Not at all, its the only way to learn.

> It will require a major effort to rewrite my use of lists in the Python 
> way and so I want to make sure that the first steps are correct.

Good idea!

> first index refers to the columns and the second to the rows.

You can use the indices any way you like but this way will
make your table appear sideways if you print it out with
print()

But...

> solution = [[0 for i in range(num_cols)] for j in range(num_rows)]

This is a list of lists.
Each inner list is  the number of *columns* wide - so it
must represent a *row* not a column.
And you have as many inner lists as you have rows so
that means each position inside a row represents a column entry.



> solution[1][0] = {5}

So this represents the second row, first column.

> ...
> solution[0][1] = {1,2,3}

And this is the first row, second column.

> for col in solution:
>  ??? print(col[0])
> for row in solution:
>  ??? print(row[1])

These two loops are both extracting the same objects,
just printing a different item. Let's rewrite it using
different names for the variable (since the loop doesn't
care about the name):

for x in solution: print(x[0])
for x in solution: print(x[1])

I reused the name x since the loop doesn't care.
But can you see how you are repeating the exact same loop.

Meaningful variable names are great because they show your
intentions. But they can trick us into thinking they
mean something that they don't, just because we want them to!

> If I want to refer to column 6, is it the Python way to say x = col[6]?

Yes, provided you have first set x to a row.
And of course 6 returns the 7th column since its
zero based indexing.

Also, using python "2D" lists there is no way to
access the entire column (in your example) you can
only access a whole row.

You can build a copy of a column easily enough with:

col6 = [row[5] for row in solution]

But if you change any values you need to regenerate
the copy so it's not exactly efficient.

> Also regarding enumeration. The following is a slight modification to 
> Mats code and it gives me exactly what I want:
> 
> row = [{7,3},{5},{4,8,6},{7,8},{1},{9,3},{7,9},{4,6,3},{2}]
> 
> enum_row = enumerate(row)

This is unused and gets thrown away as soon as
you enter the loop.

> row_position = []
> 
> for index, enum_row in enumerate(row):

enum_row is a bad name to use here IMHO.
its actually each set within the row.
And the sets represent the cell content
(as I understand your design)
So I'd prefer

for index,cell in enumerate(row):

>  ??? ??? if i in enum_row:#r:
>  ??????? ??? icount += 1
>  ??????????? row_position.append(index)

And this becomes

if i in cell:
   icount += 1
   row_position.append(index)

> Now returning to the two dimensional list above and assuming that col[0] 
> is referring to a row (just for this question only). I'm not sure if 
> this is correct because of an error in another section of the code

I think you need to swap your understanding of rows/cols.
You access the rows directly, the columns you need to
construct on demand.

col[0] doesn't refer to anything because col doesn't exist.
Even if you created the col as illustrated above col[0] would
be the first cell only, not a row.

But you can get the row using solution[0]

> enum_row = enumerate(col[0]) # instead or row

Again, I don't know what you think this is doing
but it returns a generator(pedantically, an enumerate object)
which you never use and then:

> for index, enum_row in enumerate(col[0]): # instead or row

Assuming col should be solution...

This sets enum_row to the second value of the first returned
tuple from enumerate(), ie the first row.

So now you want(I think) to test every cell within that row
using the exact code you had above. So you need two nested loops.

>  ??? print('enum_row ',enum_row )
>  ??? ??? if i in enum_row:
>  ??????? ??? icount += 1
> 
> This is where the error is occurring (also from Mats code):
> 
> for s in set_list:

Where is set_list created?

>  ??? for r in col[0]: # instead of row:
>  ??????? if s.issubset(r):
>  ??????????? pairs[tuple(sorted(s))] += 1
> 
> Traceback (most recent call last):
>  ? File "/usr/lib/python3.9/idlelib/run.py", line 559, in runcode
>  ??? exec(code, self.locals)
>  ? File "/home/phil/Python/set_count2.py", line 75, in <module>
>  ??? if s.issubset(r):
> TypeError: 'int' object is not iterable
> 
> Confusion is setting in. I think my use of enumerate is correct and I 
> think the way that I'm referencing a row from the solution list is 
> correct. 

Sadly, I think both of those assumptions are wrong!

What I think you are trying to do, and using the name
you started with is:


for irow, row in enumerate(solution):
    for icell, cell in enumerate(row):
        if value in cell:
           pairs[tuple(sorted(cell))] += 1
           table_position.append(irow,icell)  # I think...

Which hopefully reads more clearly and makes sense.

-- 
Alan G
Author of the Learn to Program web site
http://www.alan-g.me.uk/
http://www.amazon.com/author/alan_gauld
Follow my photo-blog on Flickr at:
http://www.flickr.com/photos/alangauldphotos



From phillor9 at gmail.com  Sun Nov 21 20:05:26 2021
From: phillor9 at gmail.com (Phil)
Date: Mon, 22 Nov 2021 12:05:26 +1100
Subject: [Tutor] The Python way and two dimensional lists
In-Reply-To: <dd686338-48ea-8114-190f-c9dc0a185073@gmail.com>
References: <dd686338-48ea-8114-190f-c9dc0a185073@gmail.com>
Message-ID: <ef895d8b-2f96-5f5a-8783-985d43a64596@gmail.com>

If I substitute rr where row was originally used that all is good again. 
It seems to be a bit of a work-around. Is there a more correct Python way?

rr = []

for col in solution:
 ??? print(col[0])
 ??? rr.append(col[0])

-- 

Regards,
Phil


From phillor9 at gmail.com  Sun Nov 21 20:14:10 2021
From: phillor9 at gmail.com (Phil)
Date: Mon, 22 Nov 2021 12:14:10 +1100
Subject: [Tutor] The Python way and two dimensional lists
In-Reply-To: <sneppr$ifj$1@ciao.gmane.io>
References: <dd686338-48ea-8114-190f-c9dc0a185073@gmail.com>
 <sneppr$ifj$1@ciao.gmane.io>
Message-ID: <f3cbe639-0ae7-0615-3aca-e87e675726f5@gmail.com>

Thank you Alan, you've given me a lot to digest. I knew that I was, and 
perhaps I still am, confusing rows and columns. More thought required on 
my part.

-- 

Regards,
Phil


From PyTutor at DancesWithMice.info  Sun Nov 21 20:34:45 2021
From: PyTutor at DancesWithMice.info (dn)
Date: Mon, 22 Nov 2021 14:34:45 +1300
Subject: [Tutor] The Python way and two dimensional lists
In-Reply-To: <dd686338-48ea-8114-190f-c9dc0a185073@gmail.com>
References: <dd686338-48ea-8114-190f-c9dc0a185073@gmail.com>
Message-ID: <1586327c-cc90-c889-b8cc-81c5c047ff67@DancesWithMice.info>

On 22/11/2021 13.13, Phil wrote:
> I hope my questions are not becoming too tiresome.

@Alan seems to have jumped-in first, so I've edited this response, and
hope it has not become too disjointed.

First question: have you located (and at least dipped-into) Pilgrim's
book (as mentioned earlier). He certainly discusses lists, and (I
haven't looked (again)) may well cover 2D...

Later there is a specific explanation, but the reason for reading is not
(only) that you pick-up Python-syntax, but also that you can see the
idioms of the language - the way 'bits' work together, and how the
language designers were thinking things should go (mental models make
another appearance below). Thus, time worth investing...

Incidentally, have a look at the bottom of @Alan's posts, because such
may (also) be covered in his tutorial.

(in both cases, a while since I've looked for specifics in either)


> It will require a major effort to rewrite my use of lists in the Python
> way and so I want to make sure that the first steps are correct. The
> first index refers to the columns and the second to the rows.
> 
> num_rows = 9
> num_cols = 9
> 
> solution = [[0 for i in range(num_cols)] for j in range(num_rows)]

Python's storage allocation is dynamic. It is not necessary to 'reserve'
space.


> solution[0][0] = {7,3}
> solution[1][0] = {5}
> solution[2][0] = {4,8,6}
> solution[3][0] = {7,8}
> solution[4][0] = {1}
> solution[5][0] = {9,3}
> solution[6][0] = {7,9}
> solution[7][0] = {4,6,3}
> solution[8][0] = {2}

As per @Alan, I also kept feeling that this was 'the wrong way around'!
Firstly, I'm a navigator, so I'm used to looking at Cartesian
Co-ordinate systems - across before up/down. Secondly, it shouldn't
really matter which way around one considers the rows and the columns -
so time to get my head out of ...

That said, consistency is key. If *you* don't have a visualisation (a
mental model) of how this system will work, then all is lost! (at sea?)
- and the rest of us have 'no chance'...


Next point: Python's lists are not arrays. Notably (but largely
irrelevant in this case) many languages require the elements of an array
to be of the same type. Items in Python lists can vary, as desired!

Lists are typically built either from another "collection" or
incrementally. Thus:

l = list( ( 1, 2, 3 ) )

or

l = list() # or []
l.append( 1 )
l.append( 2 )
...


...

> row = [{7,3},{5},{4,8,6},{7,8},{1},{9,3},{7,9},{4,6,3},{2}]

May I suggest that you ignore the 2D issue, for now. Work with the
above. Identify the match(es) in this one row, and prove that part of
the algorithm.


This is what we (in the business) call "Stepwise Decomposition" (plenty
of web-links). The idea is to break a large problem into smaller
problems. Then break those into even smaller problems. Continuing until
the size of the problem becomes 'easily manageable'. In your case, as a
Python-Apprentice, this might be a smaller unit than someone else, but
that is *not* important. In short everyone's definition of
'small-enough' is going to be different (aka YMMV)!

Now, with a 'small' problem, you can wrap it into a Python-function (and
when you come to linking small-solutions into the solution of a
larger-problem, it becomes a matter of stringing-together a bunch of
function calls! (he says, breezily)


This also picking-up your point about wanting to be sure that 'the core'
of the idea is correct, cf risking spending a lot of time 'flogging a
dead horse'. Conversely, and as I was reminding myself when I feared
wasting my time on testing and refactoring existing code this morning
(cf feeling I was 'solving the emergent problem, as needed') - testing
and becoming confident in the capacities of the 'building blocks'
becomes a series of small encouragements, and "nothing succeeds like
success"!


Another advantage is that you can write some (automated) tests, eg

row = [{7,3}, etc
result = find_duplicates( row )
assert result == x,y,z

(if you've not previously met "assert", its boolean-expression must
result in True, otherwise it fails - and the exception report will draw
your (much-needed) attention to the disparity!)


> Confusion is setting in. I think my use of enumerate is correct and I
> think the way that I'm referencing a row from the solution list is
> correct. If both of those aren't the source of the error then it has to
> do with my use of sets. for r in col[0] doesn't give me the sets
> {7,3},{5} etc.

This, and something you said earlier, represent other good reasons for
building short functions. Even if you don't want to risk 'breaking'
working-code, they are easy to copy-paste, and thus allow you to tinker
with a 'disposable' copy.

Such can thus be regarded as a 'test-bench' which you can use to
experiment, and compare different ideas as they occur to you. (it's what
many of us do, even if you can't see us...)


> Searching the Internet for information hasn't made me any wiser yet and
> again I'm sorry to burden the list members with my problems.

See first question (above). That said, we like intelligent questions
posed by people who make an effort...
-- 
Regards,
=dn

From phillor9 at gmail.com  Sun Nov 21 21:13:37 2021
From: phillor9 at gmail.com (Phil)
Date: Mon, 22 Nov 2021 13:13:37 +1100
Subject: [Tutor] The Python way and two dimensional lists
In-Reply-To: <1586327c-cc90-c889-b8cc-81c5c047ff67@DancesWithMice.info>
References: <dd686338-48ea-8114-190f-c9dc0a185073@gmail.com>
 <1586327c-cc90-c889-b8cc-81c5c047ff67@DancesWithMice.info>
Message-ID: <3bd3036c-a4a5-936c-f18f-b404b8885a9b@gmail.com>


On 22/11/21 12:34, dn via Tutor wrote:
> On 22/11/2021 13.13, Phil wrote:
>> I hope my questions are not becoming too tiresome.
> @Alan seems to have jumped-in first, so I've edited this response, and
> hope it has not become too disjointed.
>
> First question: have you located (and at least dipped-into) Pilgrim's
> book (as mentioned earlier). He certainly discusses lists, and (I
> haven't looked (again)) may well cover 2D...

Thank you dn, more to digest. Yes, I have downloaded the book. I found 
the suggested chapter 8 hard going and I couldn't relate it to what I'm 
doing. I've scanned some of the other chapters and will read the list 
chapter. I've added the book to my calibre library of Python books.

-- 
Regards,
Phil


From wlfraed at ix.netcom.com  Sun Nov 21 21:15:01 2021
From: wlfraed at ix.netcom.com (Dennis Lee Bieber)
Date: Sun, 21 Nov 2021 21:15:01 -0500
Subject: [Tutor] The Python way and two dimensional lists
References: <dd686338-48ea-8114-190f-c9dc0a185073@gmail.com>
Message-ID: <lrulpg9n8ha0k50076hh44c1stn9o754h2@4ax.com>

On Mon, 22 Nov 2021 11:13:15 +1100, Phil <phillor9 at gmail.com> declaimed the
following:


>
>for s in set_list:
> ??? for r in col[0]: # instead of row:
> ??????? if s.issubset(r):
> ??????????? pairs[tuple(sorted(s))] += 1
>
>Traceback (most recent call last):
> ? File "/usr/lib/python3.9/idlelib/run.py", line 559, in runcode
> ??? exec(code, self.locals)
> ? File "/home/phil/Python/set_count2.py", line 75, in <module>
> ??? if s.issubset(r):
>TypeError: 'int' object is not iterable

	Have you looked at the definition of .issubset()?

	The object one applies it to must be a set. The parameter passed must
be a superset (or equal). It returns true if the object -- in your example,
that would be	s	-- is a subset of the parameter		r	.

	But your r is not a set -- "for r in col[0]" is selecting the first
element of whatever col contains, which appears to be a single integer at
this point. I suspect you need to: 1) ensure that "r" is a SET, and
possible 2) reverse the call		r.issubset(s)



-- 
	Wulfraed                 Dennis Lee Bieber         AF6VN
	wlfraed at ix.netcom.com    http://wlfraed.microdiversity.freeddns.org/


From phillor9 at gmail.com  Sun Nov 21 22:35:30 2021
From: phillor9 at gmail.com (Phil)
Date: Mon, 22 Nov 2021 14:35:30 +1100
Subject: [Tutor] The Python way and two dimensional lists
In-Reply-To: <lrulpg9n8ha0k50076hh44c1stn9o754h2@4ax.com>
References: <dd686338-48ea-8114-190f-c9dc0a185073@gmail.com>
 <lrulpg9n8ha0k50076hh44c1stn9o754h2@4ax.com>
Message-ID: <22c41561-b7f3-5d7c-2ae2-690b252b1cbe@gmail.com>


> 	The object one applies it to must be a set. The parameter passed must
> be a superset (or equal). It returns true if the object -- in your example,
> that would be	s	-- is a subset of the parameter		r	.

Thank you Dennis,

I had posted a method I'd used to correct this problem. Although does 
work correctly. I suspect that it's not an efficient method.

-- 

Regards,
Phil


From alexkleider at gmail.com  Sun Nov 21 22:40:57 2021
From: alexkleider at gmail.com (Alex Kleider)
Date: Sun, 21 Nov 2021 19:40:57 -0800
Subject: [Tutor] curses.textpad.Textbox.gather()
Message-ID: <CAMCEyD6VVi_hMrtV7a6X145ruxbYat3ew5d5mxUNfsFtezA-Ow@mail.gmail.com>

"""
I expect this will be of interest only to those using the curses
module.

I found that the Textbox.gather method seems incapable of returning
a string without a trailing space. The problem is easily solved by
using str.strip() as in the last line of my function (provided below)
but I'm wondering if there's a better way. Specifically to provide the
user with the option of having or not having a trailing space.
"""

import sys
import curses as cur
from curses.textpad import Textbox

def edited_text(scr, text, y,x):
    """
    Provides the editing capability:
    Returns the edited (or not) version of text.
    Editing window begins at (y,x) of the <scr>een.
    """
    scr.addstr(y,0, "Edit the text then Ctrl-G to exit",
               cur.A_BOLD)
    scr.refresh()
    # create the text box with border around the outside
    tb_border = cur.newwin(3,52,y+1,x)
    tb_border.box()
    tb_border.refresh()
    tb_body = cur.newwin(1,50,y+2,x+1)
    tb = Textbox(tb_body)
    for ch in text:  # insert starting text
        tb.do_command(ch)
    tb.edit()  # start the editor running, Ctrl-G ends
    s2 = tb.gather()  # fetch the contents
    scr.clear()  # clear the screen
#   return s2
    return s2.strip()

def main(scr):
    text = "Some text to be or not to be edited."
    new_text = edited_text(scr, text, 5,4)
    scr.clear()
    scr.addstr(8,0, 'Your modified text: "{}"'.format(new_text))
    scr.getch()  # does a refresh

cur.wrapper(main)

close = """
TIA

Cheers,
Alex Kleider
"""

From phillor9 at gmail.com  Mon Nov 22 01:02:34 2021
From: phillor9 at gmail.com (Phil)
Date: Mon, 22 Nov 2021 17:02:34 +1100
Subject: [Tutor] The Python way and two dimensional lists
In-Reply-To: <sneppr$ifj$1@ciao.gmane.io>
References: <dd686338-48ea-8114-190f-c9dc0a185073@gmail.com>
 <sneppr$ifj$1@ciao.gmane.io>
Message-ID: <a04e1872-4702-3ec5-8bce-98dbaf007809@gmail.com>


> Also, using python "2D" lists there is no way to
> access the entire column (in your example) you can
> only access a whole row.

This has always confused me even when I had it working correctly using 
the non Python way. It worked so I accepted it.

I now have this:

num_rows = 9
num_cols = 9

solution = [[0 for i in range(num_cols)] for j in range(num_rows)]

# solution row column

solution[0][0] = {7,3}, {5}, {4,8,6}, {7,8}, {1}, {9,3}, {7,9}, {4,6,3}, 
{2}
solution[0][1] = {1}
solution[0][2] = {2}
solution[0][3] = {3}
solution[0][4] = {4}
solution[0][5] = {5}
solution[0][6] = {6}
solution[0][7] = {7}
solution[0][8] = {8}

So row 0 is {7,3}, {5} etc

and row 1 is {1} followed by 8 zeros

for row in solution:
 ??? print(row[0])

({3, 7}, {5}, {8, 4, 6}, {8, 7}, {1}, {9, 3}, {9, 7}, {3, 4, 6}, {2})
0
0
0
0
0
0
0
0

Why do the sets represent only one position and the eight zeros make up 
the remaining nine positions?

> You can build a copy of a column easily enough with:
>
> col6 = [row[5] for row in solution]
col0 = [row[0] for row in solution]

print('column ', col0)

prints row 0 with 8 extra zeros:

column? [({3, 7}, {5}, {8, 4, 6}, {8, 7}, {1}, {9, 3}, {9, 7}, {3, 4, 
6}, {2}), 0, 0, 0, 0, 0, 0, 0, 0]

It's those extra zeros again.

col0 = [row[6] for row in solution]
print('column ', col0)

prints and this is what I did expect:

column? [{6}, 0, 0, 0, 0, 0, 0, 0, 0]

> But if you change any values you need to regenerate
> the copy so it's not exactly efficient.

Is there a Python way to access any point on the grid with something 
like x = row[6][col7]. This is how I had originally accessed the grid. 
I'm happy to change the entire design so that I have a static grid that 
I can access with a row, col combination. Having to build a column every 
time I want to access it seems like a lot of unnecessary extra effort. 
Should I investigate the array module rather that persisting with lists? 
Arrays make more sense to me.

-- 

Regards,
Phil


From alan.gauld at yahoo.co.uk  Mon Nov 22 04:58:41 2021
From: alan.gauld at yahoo.co.uk (Alan Gauld)
Date: Mon, 22 Nov 2021 09:58:41 +0000
Subject: [Tutor] The Python way and two dimensional lists
In-Reply-To: <a04e1872-4702-3ec5-8bce-98dbaf007809@gmail.com>
References: <dd686338-48ea-8114-190f-c9dc0a185073@gmail.com>
 <sneppr$ifj$1@ciao.gmane.io> <a04e1872-4702-3ec5-8bce-98dbaf007809@gmail.com>
Message-ID: <snfpkl$cdk$1@ciao.gmane.io>

On 22/11/2021 06:02, Phil wrote:

> I now have this:
> 
> num_rows = 9
> num_cols = 9
> 
> solution = [[0 for i in range(num_cols)] for j in range(num_rows)]
> 
> # solution row column
> 
> solution[0][0] = {7,3}, {5}, {4,8,6}, {7,8}, {1}, {9,3}, {7,9}, {4,6,3}, 
> {2}

I think you actually wanted:

solution[0] = [{7,3}, {5}, {4,8,6}, {7,8}, {1}, {9,3}, {7,9}, {4,6,3},
{2}]

That initialised the first row to the list of sets.

What you have creates a tuple and inserts all of those sets into the
first cell. I'm fairly sure that's not what you meant to do.

> solution[0][1] = {1}
> solution[0][2] = {2}
> solution[0][3] = {3}
> solution[0][4] = {4}
> solution[0][5] = {5}
> solution[0][6] = {6}
> solution[0][7] = {7}
> solution[0][8] = {8}
> 
> So row 0 is {7,3}, {5} etc

No, your code made the first cell of row 0 contain all those
sets. The subsequent assignments filled the remaining cells
with 1-8 respectively.

> and row 1 is {1} followed by 8 zeros

No, you haven't put anything into row 1. So it is all
zeros (from the list comprehension).

One thing you might consider is using the Python
interactive prompt (>>>) to experiment before you
code to see what each value returns. The prompt is a
very useful tool when programming but for some reason
many programmers neglect to use it while writing code.

Another option that could work here, and is often
used in professional code, is to just do the initialisation
in a hard coded list format:

solution = [
[{7,3}, {5}, {4,8,6}, {7,8}, {1}, {9,3}, {7,9}, {4,6,3}, {2}],
[{1},0,0,0,0,0,0,0,0],
[{2},0,0,0,0,0,0,0,0],
[{3},0,0,0,0,0,0,0,0],
[{4},0,0,0,0,0,0,0,0],
[{5},0,0,0,0,0,0,0,0],
[{6},0,0,0,0,0,0,0,0],
[{7},0,0,0,0,0,0,0,0],
[{8},0,0,0,0,0,0,0,0]
]

You can then insert any other values you need into the
cells directly.

Obviously this technique isn't effective with huge data
sets, but for this purpose should work well and may help
you visualize things better.

Note that this duplicates what I think you were trying to do with your
assignments. Also note the discrepancy in data types between the zeros
you used in initialising the lists and the sets you use in your
assignments. Might it be better to initialize with empty sets
instead of 0s? (Empty sets are created with set())


> 
> for row in solution:
>  ??? print(row[0])
> 
> ({3, 7}, {5}, {8, 4, 6}, {8, 7}, {1}, {9, 3}, {9, 7}, {3, 4, 6}, {2})
> 0
> 0
> 0
> 0
> 0
> 0
> 0
> 0
> 
> Why do the sets represent only one position and the eight zeros make up 
> the remaining nine positions?

Try creating 2D lists using values other than 0 in the >>> prompt:

test_table = [[c for c in 'abcdefgh'] for  n in range(9)]

Then try printing rows and columns using the prompt and
different indices until you feel comfortable extracting
what you need. You will learn a lot that way.

>> You can build a copy of a column easily enough with:
>>
>> col6 = [row[5] for row in solution]
> col0 = [row[0] for row in solution]
> 
> print('column ', col0)
> 
> prints row 0 with 8 extra zeros:
> 
> column? [({3, 7}, {5}, {8, 4, 6}, {8, 7}, {1}, {9, 3}, {9, 7}, {3, 4, 
> 6}, {2}), 0, 0, 0, 0, 0, 0, 0, 0]
> 
> It's those extra zeros again.

Hopefully the above explanation shows where they came from.
And the interactive session has clarified what you need to do?


> col0 = [row[6] for row in solution]
> print('column ', col0)
> 
> prints and this is what I did expect:
> 
> column? [{6}, 0, 0, 0, 0, 0, 0, 0, 0]

really? It's not what I would expect!

> 
>> But if you change any values you need to regenerate
>> the copy so it's not exactly efficient.
> 
> Is there a Python way to access any point on the grid with something 
> like x = row[6][col7]. This is how I had originally accessed the grid. 

Yes that's exactly what you can do using 2 indices.
What you can't do is access whole columns.

> I'm happy to change the entire design so that I have a static grid that 
> I can access with a row, col combination. Having to build a column every 
> time I want to access it seems like a lot of unnecessary extra effort. 
> Should I investigate the array module rather that persisting with lists? 
> Arrays make more sense to me.

There is very little difference in python between arrays and lists.
But lists are such a flexible and all pervasive data structure in
Python that you really should stick with them. They are a fundamental
skill for every Python user.

Just remember that row and column are solution concepts that
Python does not understand. All python knows is that a list
is a sequence of values that can be accessed using an index.
Those values may or may not be other lists.

In a 2D list structure the top level list does not know that the
sublists are lists. To it they are just value objects like
any other. It certainly doesn't know that they represent a
table with rows and columns. That concept resides solely
in the programmer's(ie. your) head.


-- 
Alan G
Author of the Learn to Program web site
http://www.alan-g.me.uk/
http://www.amazon.com/author/alan_gauld
Follow my photo-blog on Flickr at:
http://www.flickr.com/photos/alangauldphotos



From alan.gauld at yahoo.co.uk  Mon Nov 22 05:14:59 2021
From: alan.gauld at yahoo.co.uk (Alan Gauld)
Date: Mon, 22 Nov 2021 10:14:59 +0000
Subject: [Tutor] curses.textpad.Textbox.gather()
In-Reply-To: <CAMCEyD6VVi_hMrtV7a6X145ruxbYat3ew5d5mxUNfsFtezA-Ow@mail.gmail.com>
References: <CAMCEyD6VVi_hMrtV7a6X145ruxbYat3ew5d5mxUNfsFtezA-Ow@mail.gmail.com>
Message-ID: <snfqj6$ds5$1@ciao.gmane.io>

On 22/11/2021 03:40, Alex Kleider wrote:
> """
> I expect this will be of interest only to those using the curses
> module.
> 
> I found that the Textbox.gather method seems incapable of returning
> a string without a trailing space. 

So it seems although I'd not noticed until,your post...

> but I'm wondering if there's a better way. Specifically to provide the
> user with the option of having or not having a trailing space.

As you say its easy to remove the spaces with rstrip()
And its equally easy to add a space if needed.
So you could write a wrapper that took a space parameter and
added/removed spaces as needed.

>     # create the text box with border around the outside
>     tb_border = cur.newwin(3,52,y+1,x)
>     tb_border.box()
>     tb_border.refresh()
>     tb_body = cur.newwin(1,50,y+2,x+1)
>     tb = Textbox(tb_body)
>     for ch in text:  # insert starting text
>         tb.do_command(ch)
>     tb.edit()  # start the editor running, Ctrl-G ends
>     s2 = tb.gather()  # fetch the contents

Hmm, this all feels oddly familiar.... :-)


-- 
Alan G
Author of the Learn to Program web site
http://www.alan-g.me.uk/
http://www.amazon.com/author/alan_gauld
Follow my photo-blog on Flickr at:
http://www.flickr.com/photos/alangauldphotos



From alexkleider at gmail.com  Mon Nov 22 11:43:37 2021
From: alexkleider at gmail.com (Alex Kleider)
Date: Mon, 22 Nov 2021 08:43:37 -0800
Subject: [Tutor] curses.textpad.Textbox.gather()
In-Reply-To: <snfqj6$ds5$1@ciao.gmane.io>
References: <CAMCEyD6VVi_hMrtV7a6X145ruxbYat3ew5d5mxUNfsFtezA-Ow@mail.gmail.com>
 <snfqj6$ds5$1@ciao.gmane.io>
Message-ID: <CAMCEyD6ULorgWVQn-UZAMYHoYON4yPeXj2sxP7f3Qhw3Qcmpvg@mail.gmail.com>

>
> Hmm, this all feels oddly familiar.... :-)
>

Blatant plagiarism for sure!
Remember, "imitation is the most sincere form of flattery."

On a more serious note, Bob Stepp sent me a link which sounded promising
but his followup indicated not so.  I haven't looked into it yet.

All the best (to both of you, and indeed to the whole list.)
Alex

>
> ___________________________________________
>
<https://mail.python.org/mailman/listinfo/tutor>

From wlfraed at ix.netcom.com  Mon Nov 22 11:45:40 2021
From: wlfraed at ix.netcom.com (Dennis Lee Bieber)
Date: Mon, 22 Nov 2021 11:45:40 -0500
Subject: [Tutor] The Python way and two dimensional lists
References: <dd686338-48ea-8114-190f-c9dc0a185073@gmail.com>
 <sneppr$ifj$1@ciao.gmane.io> <a04e1872-4702-3ec5-8bce-98dbaf007809@gmail.com>
Message-ID: <eehnpgd448fsocpnprpcnf7epmg118gufl@4ax.com>

On Mon, 22 Nov 2021 17:02:34 +1100, Phil <phillor9 at gmail.com> declaimed the
following:

>
>solution[0][0] = {7,3}, {5}, {4,8,6}, {7,8}, {1}, {9,3}, {7,9}, {4,6,3}, 
>{2}
>
>So row 0 is {7,3}, {5} etc
>
>and row 1 is {1} followed by 8 zeros
>
>for row in solution:
> ??? print(row[0])
>
>({3, 7}, {5}, {8, 4, 6}, {8, 7}, {1}, {9, 3}, {9, 7}, {3, 4, 6}, {2})

>
>Why do the sets represent only one position and the eight zeros make up 
>the remaining nine positions?
>
	Because that is what you told it to be... Note the () around the
printed value -- that indicates a tuple. Tuples don't need (), they need
the comma.

	You bound the nine-element tuple to the [0][0] element of your
list-of-lists. Python does not automatically unpack tuples unless you
provide enough destination spaces for it.

>>> solution[0][0:8] = {7,3}, {5}, {4,8,6}, {7,8}, {1}, {9,3}, {7,9}, {4,6,3}, {2}

	Here I provide 9 destination spaces for the nine elements on the right.

>>> print(solution[0])
[{3, 7}, {5}, {8, 4, 6}, {8, 7}, {1}, {9, 3}, {9, 7}, {3, 4, 6}, {2}, [2]]
>>> 

	And here is a LIST of nine elements as the result, and they are
individually accessible

>>> solution[0][1]
{5}
>>> 

	The other way is to provide a LIST on the right side

>>> solution2 = [0] * 9

	Create a nine element (column) list

>>> solution2
[0, 0, 0, 0, 0, 0, 0, 0, 0]
>>> solution2[0] = [	{7,3}, {5}, {4,8,6}, {7,8}, {1}, {9,3}, {7,9}, {4,6,3}, {2}	]

	Replace the first element with the nine element (row) list

>>> solution2
[[{3, 7}, {5}, {8, 4, 6}, {8, 7}, {1}, {9, 3}, {9, 7}, {3, 4, 6}, {2}], 0,
0, 0, 0, 0, 0, 0, 0]
>>> solution2[0]
[{3, 7}, {5}, {8, 4, 6}, {8, 7}, {1}, {9, 3}, {9, 7}, {3, 4, 6}, {2}]
>>> solution2[0][1]
{5}
>>> 


-- 
	Wulfraed                 Dennis Lee Bieber         AF6VN
	wlfraed at ix.netcom.com    http://wlfraed.microdiversity.freeddns.org/


From wlfraed at ix.netcom.com  Mon Nov 22 12:13:42 2021
From: wlfraed at ix.netcom.com (Dennis Lee Bieber)
Date: Mon, 22 Nov 2021 12:13:42 -0500
Subject: [Tutor] The Python way and two dimensional lists
References: <dd686338-48ea-8114-190f-c9dc0a185073@gmail.com>
 <sneppr$ifj$1@ciao.gmane.io> <a04e1872-4702-3ec5-8bce-98dbaf007809@gmail.com>
 <eehnpgd448fsocpnprpcnf7epmg118gufl@4ax.com>
Message-ID: <mpinpghgjohr8gigtaircok7o50a8vefvh@4ax.com>

On Mon, 22 Nov 2021 11:45:40 -0500, Dennis Lee Bieber
<wlfraed at ix.netcom.com> declaimed the following:


>
>>>> solution[0][0:8] = {7,3}, {5}, {4,8,6}, {7,8}, {1}, {9,3}, {7,9}, {4,6,3}, {2}
>
>	Here I provide 9 destination spaces for the nine elements on the right.
>
	Whoops... slight miscount (and the next is showing where I had a
previous error... Let me try again...


	Create 9x9 of empty sets

>>> solution = [ [ set() for _ in range(9)] for _ in range(9)] 
>>> solution
[[set(), set(), set(), set(), set(), set(), set(), set(), set()], [set(),
set(), set(), set(), set(), set(), set(), set(), set()], [set(), set(),
set(), set(), set(), set(), set(), set(), set()], [set(), set(), set(),
set(), set(), set(), set(), set(), set()], [set(), set(), set(), set(),
set(), set(), set(), set(), set()], [set(), set(), set(), set(), set(),
set(), set(), set(), set()], [set(), set(), set(), set(), set(), set(),
set(), set(), set()], [set(), set(), set(), set(), set(), set(), set(),
set(), set()], [set(), set(), set(), set(), set(), set(), set(), set(),
set()]]


	Bind 9 element tuple to the 9 spaces in the first "row"

>>> solution[0][0:9] = {7,3}, {5}, {4,8,6}, {7,8}, {1}, {9,3}, {7,9}, {4,6,3}, {2}
>>> solution
[[{3, 7}, {5}, {8, 4, 6}, {8, 7}, {1}, {9, 3}, {9, 7}, {3, 4, 6}, {2}],
[set(), set(), set(), set(), set(), set(), set(), set(), set()], [set(),
set(), set(), set(), set(), set(), set(), set(), set()], [set(), set(),
set(), set(), set(), set(), set(), set(), set()], [set(), set(), set(),
set(), set(), set(), set(), set(), set()], [set(), set(), set(), set(),
set(), set(), set(), set(), set()], [set(), set(), set(), set(), set(),
set(), set(), set(), set()], [set(), set(), set(), set(), set(), set(),
set(), set(), set()], [set(), set(), set(), set(), set(), set(), set(),
set(), set()]]


	Extract first row

>>> solution[0]
[{3, 7}, {5}, {8, 4, 6}, {8, 7}, {1}, {9, 3}, {9, 7}, {3, 4, 6}, {2}]


	Extract third column from first row

>>> solution[0][2]
{8, 4, 6}
>>> 


-- 
	Wulfraed                 Dennis Lee Bieber         AF6VN
	wlfraed at ix.netcom.com    http://wlfraed.microdiversity.freeddns.org/


From kaushalshriyan at gmail.com  Mon Nov 22 11:48:19 2021
From: kaushalshriyan at gmail.com (Kaushal Shriyan)
Date: Mon, 22 Nov 2021 22:18:19 +0530
Subject: [Tutor] Enable Python feature in vim editor
Message-ID: <CAD7Ssm9OAqopu7fkF+Fjjy7A-2fVJLqbQ6bw3da1JMwe_SS9zw@mail.gmail.com>

Hi,

I am using vim editor to write python scripts. Is there a way to enable
syntax, help and indentation of python script?

Thanks in advance. I look forward to hearing from you.

Best Regards,

Kaushal

From leamhall at gmail.com  Mon Nov 22 14:06:35 2021
From: leamhall at gmail.com (Leam Hall)
Date: Mon, 22 Nov 2021 13:06:35 -0600
Subject: [Tutor] Enable Python feature in vim editor
In-Reply-To: <CAD7Ssm9OAqopu7fkF+Fjjy7A-2fVJLqbQ6bw3da1JMwe_SS9zw@mail.gmail.com>
References: <CAD7Ssm9OAqopu7fkF+Fjjy7A-2fVJLqbQ6bw3da1JMwe_SS9zw@mail.gmail.com>
Message-ID: <855852f9-3481-2b87-4a4c-9108a90c4002@gmail.com>

Hey Kaushal,

Here's part of my ~/.vimrc. You can do a lot with it, and there are likely Python specific plugins.

###
set shiftwidth=2
set shiftround
set tabstop=4
set softtabstop=4
set noexpandtab
set number
set ruler
set noautoindent
set nosmartindent
set noincsearch

syntax enable
###

On 11/22/21 10:48, Kaushal Shriyan wrote:
> Hi,
> 
> I am using vim editor to write python scripts. Is there a way to enable
> syntax, help and indentation of python script?
> 
> Thanks in advance. I look forward to hearing from you.
> 
> Best Regards,
> 
> Kaushal

-- 
Systems Programmer         (reuel.net/resume)
Scribe: The Domici War     (domiciwar.net)
General Ne'er-do-well      (github.com/LeamHall)

From learn2program at gmail.com  Mon Nov 22 14:12:55 2021
From: learn2program at gmail.com (Alan Gauld)
Date: Mon, 22 Nov 2021 19:12:55 +0000
Subject: [Tutor] Enable Python feature in vim editor
In-Reply-To: <CAD7Ssm9OAqopu7fkF+Fjjy7A-2fVJLqbQ6bw3da1JMwe_SS9zw@mail.gmail.com>
References: <CAD7Ssm9OAqopu7fkF+Fjjy7A-2fVJLqbQ6bw3da1JMwe_SS9zw@mail.gmail.com>
Message-ID: <4fad91b0-3cfa-27c9-531f-16db0a5f111c@yahoo.co.uk>


On 22/11/2021 16:48, Kaushal Shriyan wrote:
> I am using vim editor to write python scripts. Is there a way to enable
> syntax, help and indentation of python script?

vim can do most things but you need to configure it.

Out of the box it should do syntax highlighting and content aware
indentation
when editing a .py script.

You can modify the colour scheme etc. too

You can also turn on various? advanced features. There are several YouTube
videos showing you how. Just search for "vim and Python"

If, OYOH you want to trurn on Python mode for writing vim macros then
you need a build of vim with Python included in the build. If you have
that you can enable python macros using an option, google is your friend!

If that doesn't get you the answer come back here, several of us, including
me, use vim as our primary editor for python.? The problem is I've been
doing so for ages and can't recall all the options I've turned on/off
over the years! But I'm happy to hunt for anything specific you need.

I might even learn some new tricks myself! :-)

-- 

Alan G
Author of the Learn to Program web site
http://www.alan-g.me.uk/
http://www.amazon.com/author/alan_gauld
Follow my photo-blog on Flickr at:
http://www.flickr.com/photos/alangauldphotos


From alexkleider at gmail.com  Mon Nov 22 14:45:07 2021
From: alexkleider at gmail.com (Alex Kleider)
Date: Mon, 22 Nov 2021 11:45:07 -0800
Subject: [Tutor] Enable Python feature in vim editor
In-Reply-To: <CAD7Ssm9OAqopu7fkF+Fjjy7A-2fVJLqbQ6bw3da1JMwe_SS9zw@mail.gmail.com>
References: <CAD7Ssm9OAqopu7fkF+Fjjy7A-2fVJLqbQ6bw3da1JMwe_SS9zw@mail.gmail.com>
Message-ID: <CAMCEyD5UB7dcmX91weXwpUnqQXCB-9BgbwUzE3D=x6FFKR9qjQ@mail.gmail.com>

Since Leam provided his .vimrc I thought I'd do the same.
(Thanks, Leam. I'm interested in having a close look at it.)
It's commented enough that hopefully you'll be able to make sense of the
plugin(s).  If I remember correctly my main goal regarding the plugin(s)
was to get automatic tag completion when editing html/xml etc (which I
seldom do anymore.)
I'm sending it as an attachment since I believe text_only attachments do
come through- if not (and you are interested) let me know and I'll resend
(in the email body.)
My other motive is to see if anyone has any comments/criticism
(constructive or otherwise.)
Alex

On Mon, Nov 22, 2021 at 11:00 AM Kaushal Shriyan <kaushalshriyan at gmail.com>
wrote:

> Hi,
>
> I am using vim editor to write python scripts. Is there a way to enable
> syntax, help and indentation of python script?
>
> Thanks in advance. I look forward to hearing from you.
>
> Best Regards,
>
> Kaushal
> _______________________________________________
> Tutor maillist  -  Tutor at python.org
> To unsubscribe or change subscription options:
> https://mail.python.org/mailman/listinfo/tutor
>

From phillor9 at gmail.com  Mon Nov 22 15:05:41 2021
From: phillor9 at gmail.com (Phil)
Date: Tue, 23 Nov 2021 07:05:41 +1100
Subject: [Tutor] The Python way and two dimensional lists
In-Reply-To: <snfpkl$cdk$1@ciao.gmane.io>
References: <dd686338-48ea-8114-190f-c9dc0a185073@gmail.com>
 <sneppr$ifj$1@ciao.gmane.io> <a04e1872-4702-3ec5-8bce-98dbaf007809@gmail.com>
 <snfpkl$cdk$1@ciao.gmane.io>
Message-ID: <b6f290e7-063c-8e64-3d1b-b4cb6ece1856@gmail.com>


> I think you actually wanted:
>
> solution[0] = [{7,3}, {5}, {4,8,6}, {7,8}, {1}, {9,3}, {7,9}, {4,6,3},
> {2}]
>
Thank you once again Alan for your helpful advice.

Once I'd given myself a chance to give this some thought I realised my 
mistake. I'd been fixated on doing things the Python way.


> One thing you might consider is using the Python
> interactive prompt

I use VS Code for my main projects and IDLE for simple tasks like this 
one and often, maybe not often enough, use the interactive prompt to 
test ideas.


> Another option that could work here, and is often
> used in professional code, is to just do the initialisation
> in a hard coded list format:

That's the way I had originally set up the grid. I thought I was acting 
like the big boys by using list comprehension.


> Obviously this technique isn't effective with huge data
> sets, but for this purpose should work well and may help
> you visualize things better.

I use grids and look-up tables in many of my projects and hard coding 
them ensures that they are the right way around instead of sideways. 
I've always found the list comprehension method anything but comprehensible.

-- 

Regards,
Phil


From phillor9 at gmail.com  Mon Nov 22 15:19:37 2021
From: phillor9 at gmail.com (Phil)
Date: Tue, 23 Nov 2021 07:19:37 +1100
Subject: [Tutor] The Python way and two dimensional lists
In-Reply-To: <mpinpghgjohr8gigtaircok7o50a8vefvh@4ax.com>
References: <dd686338-48ea-8114-190f-c9dc0a185073@gmail.com>
 <sneppr$ifj$1@ciao.gmane.io> <a04e1872-4702-3ec5-8bce-98dbaf007809@gmail.com>
 <eehnpgd448fsocpnprpcnf7epmg118gufl@4ax.com>
 <mpinpghgjohr8gigtaircok7o50a8vefvh@4ax.com>
Message-ID: <f1beae67-fc62-a513-fc56-565fc2e6e831@gmail.com>


> 	Create 9x9 of empty sets
>
>>>> solution = [ [ set() for _ in range(9)] for _ in range(9)]
>>>> solution

Thanks Dennis. I had originally used 'None' where you have 'set()'.


> 	Bind 9 element tuple to the 9 spaces in the first "row"
>
>>>> solution[0][0:9] = {7,3}, {5}, {4,8,6}, {7,8}, {1}, {9,3}, {7,9}, {4,6,3}, {2}
>>>> solution

I haven't seen slicing used that way before. I'll keep it in mind.

-- 

Regards,
Phil


From learn2program at gmail.com  Mon Nov 22 18:36:59 2021
From: learn2program at gmail.com (Alan Gauld)
Date: Mon, 22 Nov 2021 23:36:59 +0000
Subject: [Tutor] Enable Python feature in vim editor
In-Reply-To: <CAMCEyD5UB7dcmX91weXwpUnqQXCB-9BgbwUzE3D=x6FFKR9qjQ@mail.gmail.com>
References: <CAD7Ssm9OAqopu7fkF+Fjjy7A-2fVJLqbQ6bw3da1JMwe_SS9zw@mail.gmail.com>
 <CAMCEyD5UB7dcmX91weXwpUnqQXCB-9BgbwUzE3D=x6FFKR9qjQ@mail.gmail.com>
Message-ID: <7b90e0aa-6535-6ac5-6731-26581bc9f7ea@yahoo.co.uk>


On 22/11/2021 19:45, Alex Kleider wrote:
> I'm sending it as an attachment since I believe text_only attachments do
> come through- if not (and you are interested) let me know and I'll resend
> (in the email body.)

I can't see it. I think its .txt attachments that come thru' An
unextended filename
would probably be regarded as potentially dangerous.

-- 

Alan G
Author of the Learn to Program web site
http://www.alan-g.me.uk/
http://www.amazon.com/author/alan_gauld
Follow my photo-blog on Flickr at:
http://www.flickr.com/photos/alangauldphotos


From alan.gauld at yahoo.co.uk  Mon Nov 22 18:56:34 2021
From: alan.gauld at yahoo.co.uk (Alan Gauld)
Date: Mon, 22 Nov 2021 23:56:34 +0000
Subject: [Tutor] The Python way and two dimensional lists
In-Reply-To: <b6f290e7-063c-8e64-3d1b-b4cb6ece1856@gmail.com>
References: <dd686338-48ea-8114-190f-c9dc0a185073@gmail.com>
 <sneppr$ifj$1@ciao.gmane.io> <a04e1872-4702-3ec5-8bce-98dbaf007809@gmail.com>
 <snfpkl$cdk$1@ciao.gmane.io> <b6f290e7-063c-8e64-3d1b-b4cb6ece1856@gmail.com>
Message-ID: <snhani$14m0$1@ciao.gmane.io>

On 22/11/2021 20:05, Phil wrote:

>> One thing you might consider is using the Python
>> interactive prompt
> 
> I use VS Code for my main projects and IDLE for simple tasks like this 
> one and often, maybe not often enough, use the interactive prompt to 
> test ideas.

When I'm coding a big project I have 3 windows open:
1) The editor or IDE I'm using(depends on language)
2) The interactive interpreter (depends on language)
3) an OS prompt set to run the program (I don't
fully trust IDE tools to run my code, I always do
a final test as an end user would)


In (1) I edit, debug, navigate and version control my code
In (2) I try out ideas, test function operations etc.
       Often copying code snippets from her into the editor.
In (3) I run the "working" code from the IDE. Its amazing
how often new errors or warnings pop up when you run
code outside of the development tools!

Nowadays there will almost certainly be a few web pages
open too...

But if there is an interpreter I'll almost always use it.
Smalltalk programmers have the best implementation of
this way of working. Python's implementation is a close
second IMHO. Lisp programmers are another group who
have traditionally worked this way.

>> Another option that could work here, and is often
>> used in professional code, is to just do the initialisation
>> in a hard coded list format:
> 
> That's the way I had originally set up the grid. I thought I was acting 
> like the big boys by using list comprehension.

comprehensions are fine in some situations, especially
single dimensions or if the initial data is derivable
by formula(eg a constant). But if the data is arbitrary
 - like a Sudoku starting position - then the static
code approach is much easier to read, write and edit.

> I've always found the list comprehension method anything but comprehensible.

They can quickly become incomprehensible, especially when
dealing with multiple dimensions. Splitting the comp into
multiple lines often helps, but somehow seems to go
against the idea of a cmp in the first place....
For example:

solution = [[somefunc(i)
                for i in data
                   if i > limit]
             for n in range(20)]

But then unwinding to regular code looks clearer still:

solution = []
for n in range(20):
    row = []
    for i in data:
       if i > limit: row.append(somefunc(i))

The art is in deciding which approach is most maintainable
and performant(if that's significant, it usually isn't)

-- 
Alan G
Author of the Learn to Program web site
http://www.alan-g.me.uk/
http://www.amazon.com/author/alan_gauld
Follow my photo-blog on Flickr at:
http://www.flickr.com/photos/alangauldphotos



From alan.gauld at yahoo.co.uk  Mon Nov 22 18:59:58 2021
From: alan.gauld at yahoo.co.uk (Alan Gauld)
Date: Mon, 22 Nov 2021 23:59:58 +0000
Subject: [Tutor] The Python way and two dimensional lists
In-Reply-To: <f1beae67-fc62-a513-fc56-565fc2e6e831@gmail.com>
References: <dd686338-48ea-8114-190f-c9dc0a185073@gmail.com>
 <sneppr$ifj$1@ciao.gmane.io> <a04e1872-4702-3ec5-8bce-98dbaf007809@gmail.com>
 <eehnpgd448fsocpnprpcnf7epmg118gufl@4ax.com>
 <mpinpghgjohr8gigtaircok7o50a8vefvh@4ax.com>
 <f1beae67-fc62-a513-fc56-565fc2e6e831@gmail.com>
Message-ID: <snhau4$cpo$1@ciao.gmane.io>

On 22/11/2021 20:19, Phil wrote:

>>>>> solution[0][0:9] = {7,3}, {5}, {4,8,6}, {7,8}, {1}, {9,3}, {7,9}, {4,6,3}, {2}
>>>>> solution
> 
> I haven't seen slicing used that way before. I'll keep it in mind.

slice assignments are powerful but very easy to get wrong
(off by one errors etc). Even Denis got it wrong first time
round!

That's why I prefer the more direct approach:

solution[0] = [{7,3},{5},{4,8,6},{7,8},{1},{9,3},{7,9},{4,6,3},{2}]

-- 
Alan G
Author of the Learn to Program web site
http://www.alan-g.me.uk/
http://www.amazon.com/author/alan_gauld
Follow my photo-blog on Flickr at:
http://www.flickr.com/photos/alangauldphotos



From alexkleider at gmail.com  Mon Nov 22 19:47:32 2021
From: alexkleider at gmail.com (Alex Kleider)
Date: Mon, 22 Nov 2021 16:47:32 -0800
Subject: [Tutor] Enable Python feature in vim editor
In-Reply-To: <7b90e0aa-6535-6ac5-6731-26581bc9f7ea@yahoo.co.uk>
References: <CAD7Ssm9OAqopu7fkF+Fjjy7A-2fVJLqbQ6bw3da1JMwe_SS9zw@mail.gmail.com>
 <CAMCEyD5UB7dcmX91weXwpUnqQXCB-9BgbwUzE3D=x6FFKR9qjQ@mail.gmail.com>
 <7b90e0aa-6535-6ac5-6731-26581bc9f7ea@yahoo.co.uk>
Message-ID: <CAMCEyD5egWhnx-toGRqn7fj1HXvXRyHE2CjY+U9CZBT-eO2sRQ@mail.gmail.com>

Foolish of me not to have added the ".txt" suffix.
Hopefully this'll come thru.

Vundle appears to be a way of managing vim plugins and I use it to give me
tag completion: not related to Python at all. It involved 'git clone'ing
two repos into the appropriate ~/.vim subdirectory ('bundle').

I remember spending a lot of time figuring out how to make copy and paste
work.  Also not related to Python except indirectly: I use it a lot to copy
paste pearls I glean from this mailing list (and other sources) into my
~/Notes/Py/.. files.

On Mon, Nov 22, 2021 at 3:38 PM Alan Gauld <learn2program at gmail.com> wrote:

>
> On 22/11/2021 19:45, Alex Kleider wrote:
> > I'm sending it as an attachment since I believe text_only attachments do
> > come through- if not (and you are interested) let me know and I'll resend
> > (in the email body.)
>
> I can't see it. I think its .txt attachments that come thru' An
> unextended filename
> would probably be regarded as potentially dangerous.
>
> --
>
> Alan G
> Author of the Learn to Program web site
> http://www.alan-g.me.uk/
> http://www.amazon.com/author/alan_gauld
> Follow my photo-blog on Flickr at:
> http://www.flickr.com/photos/alangauldphotos
>
> _______________________________________________
> Tutor maillist  -  Tutor at python.org
> To unsubscribe or change subscription options:
> https://mail.python.org/mailman/listinfo/tutor
>
-------------- next part --------------
set autoindent
set shiftwidth=4  " number of spaces line is moved by << or >>
set expandtab     " change tab to requred number of spaces
set tabstop=4     " width of tab
set softtabstop=4 " columns of whitespace removed by backspace
set textwidth=70
set scrolljump=2
set scrolloff=2   " Keep at least n lines above/below cursor
" set mousehide     " Hide the mouse when typing
" set number        " Set line numbering
syntax on

" In insert mode, use ctrl+v to insert your system's clipboard content
" (Paste mode)   ! from Aaron:
imap <C-v> <Esc>:set paste<CR>"+P :set nopaste<CR>a

" The following is to do with Vundle:   !!! VUNDLE  !!!
" https://www.linuxfordevices.com/tutorials/linux/vundle
set nocompatible              " be iMproved, required
filetype off                  " required

" set the runtime path to include Vundle and initialize Vundle
" The directory should be changed in case you download it somewhere else
set rtp+=~/.vim/bundle/Vundle.vim
call vundle#begin()    " VundleBeginListing

" let Vundle manage Vundle, required
Plugin 'VundleVim/Vundle.vim'

" All the plugins to be installed are to be mentioned here
" inside the vundle#begin and vundle#end

Plugin 'alvan/vim-closetag'

call vundle#end()           " VundleEndListing
filetype plugin indent on   " required
" ...end of Vundle.                   !!! VundleEnd  !!

let g:closetag_filenames = '*.html,*.xhtml,*.phtml'

" Don't know where the following came from or what it does:
if has("autocmd")
   au BufReadPost * if line("'\"") > 1 && line("'\"") <= line("$") | exe "normal! g'\"" | endif
endif

From alexkleider at gmail.com  Mon Nov 22 19:59:56 2021
From: alexkleider at gmail.com (Alex Kleider)
Date: Mon, 22 Nov 2021 16:59:56 -0800
Subject: [Tutor] The Python way and two dimensional lists
In-Reply-To: <snhani$14m0$1@ciao.gmane.io>
References: <dd686338-48ea-8114-190f-c9dc0a185073@gmail.com>
 <sneppr$ifj$1@ciao.gmane.io> <a04e1872-4702-3ec5-8bce-98dbaf007809@gmail.com>
 <snfpkl$cdk$1@ciao.gmane.io> <b6f290e7-063c-8e64-3d1b-b4cb6ece1856@gmail.com>
 <snhani$14m0$1@ciao.gmane.io>
Message-ID: <CAMCEyD4sRWZUgLtu+kL_jQa-x6metRsa5tWgGtzdpBvoB3oyDQ@mail.gmail.com>

When I'm coding a big project I have 3 windows open:

> 1) The editor or IDE I'm using(depends on language)
> 2) The interactive interpreter (depends on language)
> 3) an OS prompt set to run the program (I don't
> fully trust IDE tools to run my code, I always do
> a final test as an end user would)
>
>
> In (1) I edit, debug, navigate and version control my code
> In (2) I try out ideas, test function operations etc.
>        Often copying code snippets from her into the editor.
>

So (assuming you use vim) you must also have set vim up to allow copy/paste
to/from system clipboard & vim.  I'd be interested how you did that.
(Perhaps it's set up that way by default in some Linux distributions but
not so for Debian/GNU Linux (the last two releases.)

From phillor9 at gmail.com  Mon Nov 22 22:33:40 2021
From: phillor9 at gmail.com (Phil)
Date: Tue, 23 Nov 2021 14:33:40 +1100
Subject: [Tutor] The Python way and two dimensional lists
In-Reply-To: <snhani$14m0$1@ciao.gmane.io>
References: <dd686338-48ea-8114-190f-c9dc0a185073@gmail.com>
 <sneppr$ifj$1@ciao.gmane.io> <a04e1872-4702-3ec5-8bce-98dbaf007809@gmail.com>
 <snfpkl$cdk$1@ciao.gmane.io> <b6f290e7-063c-8e64-3d1b-b4cb6ece1856@gmail.com>
 <snhani$14m0$1@ciao.gmane.io>
Message-ID: <4a8f4afe-0014-462e-6957-fa702c9b2237@gmail.com>


On 23/11/21 10:56, Alan Gauld via Tutor wrote:
>
> When I'm coding a big project I have 3 windows open:
> 1) The editor or IDE I'm using(depends on language)
> 2) The interactive interpreter (depends on language)
> 3) an OS prompt set to run the program (I don't
> fully trust IDE tools to run my code, I always do
> a final test as an end user would)

I only have a smallish laptop and so I don't have enough screen space to 
view multiple windows. VS Code takes up the whole screen but I sometimes 
have IDLE running at the same time so that I can copy working bits to VS 
Code.

I now have my Sudoku solver fully working in Python (I built the same 
project almost 20 years ago with QT and C++ and although it works, the 
code is a real mess). All I have to do now is modify some bits so that 
they comply with the Python way and remove the debugging print statements.

-- 

Regards,
Phil


From alexkleider at gmail.com  Tue Nov 23 02:38:48 2021
From: alexkleider at gmail.com (Alex Kleider)
Date: Mon, 22 Nov 2021 23:38:48 -0800
Subject: [Tutor] python programming using the vim editor (was 'The Python
 way..')
Message-ID: <CAMCEyD75tSb33RkeN_==iLCWMcMLcQcHKPR=mgQB4Dc74c7Dnw@mail.gmail.com>

Bob Stepp wrote:
"""
Do you have a system clipboard setup?  I had to get xsel going to use it
with
Neovim.

Once you have a recognized (by Vim/Neovim) system clipboard configured, then
you use the appropriate register(s).  In Vim/Neovim type ":h registers",
which
will describe them.  For instance if I have copied something to the system
clipboard with the mouse and I am back in Vim/Neovim in insert mode I type
"Ctrl-r, +" to paste it in.  If you are in normal mode you would use either
"p" or "P" as you would with one of the alphabetic registers, but instead
substitute "+".
"""
Thanks for your attempt to help, Bob, but I must confess to not
understanding!
I don't know of xsel or of Neovim.  I do have copy and paste working using
just leftclick+C(opy or leftclick+Paste and am happy with that.
I assume (but am not certain and for sure don't understand what the line is
really doing) that the following line:
" imap <C-v> <Esc>:set paste<CR>"+P :set nopaste<CR>a"
in my .vimrc is providing me that functionality .
Having said that, I did copy some of this text into the system clipboard
and then while in insert mode in vim, "Ctrl-r, +" did accomplish a paste
(the same as if I'd done 'leftclick, p'! )  That's good to know.
How do you 'copy' a highlighted segment from vim into your system clipboard?
Cheers,
Alex

From alan.gauld at yahoo.co.uk  Tue Nov 23 03:58:31 2021
From: alan.gauld at yahoo.co.uk (Alan Gauld)
Date: Tue, 23 Nov 2021 08:58:31 +0000
Subject: [Tutor] The Python way and two dimensional lists
In-Reply-To: <CAMCEyD4sRWZUgLtu+kL_jQa-x6metRsa5tWgGtzdpBvoB3oyDQ@mail.gmail.com>
References: <dd686338-48ea-8114-190f-c9dc0a185073@gmail.com>
 <sneppr$ifj$1@ciao.gmane.io> <a04e1872-4702-3ec5-8bce-98dbaf007809@gmail.com>
 <snfpkl$cdk$1@ciao.gmane.io> <b6f290e7-063c-8e64-3d1b-b4cb6ece1856@gmail.com>
 <snhani$14m0$1@ciao.gmane.io>
 <CAMCEyD4sRWZUgLtu+kL_jQa-x6metRsa5tWgGtzdpBvoB3oyDQ@mail.gmail.com>
Message-ID: <sniafn$2k7$1@ciao.gmane.io>

On 23/11/2021 00:59, Alex Kleider wrote:
> When I'm coding a big project I have 3 windows open:
> 
>> 1) The editor or IDE I'm using(depends on language)
>> 2) The interactive interpreter (depends on language)
>> 3) an OS prompt set to run the program (I don't
>> fully trust IDE tools to run my code, I always do
>> a final test as an end user would)
>>
>>
>> In (1) I edit, debug, navigate and version control my code
>> In (2) I try out ideas, test function operations etc.
>>        Often copying code snippets from her into the editor.
>>
> 
> So (assuming you use vim) you must also have set vim up to allow copy/paste
> to/from system clipboard & vim.  I'd be interested how you did that.

I use gvim which has buttons on the toolbar for that.

If I use console vim I use the regular X cut n paste
using the middle mouse button. There are vim tools for
doing it, including accessing multiple clipboards etc,
but I never use those.

-- 
Alan G
Author of the Learn to Program web site
http://www.alan-g.me.uk/
http://www.amazon.com/author/alan_gauld
Follow my photo-blog on Flickr at:
http://www.flickr.com/photos/alangauldphotos



From robertvstepp at gmail.com  Tue Nov 23 09:11:50 2021
From: robertvstepp at gmail.com (boB Stepp)
Date: Tue, 23 Nov 2021 08:11:50 -0600
Subject: [Tutor] python programming using the vim editor (was 'The
 Python way..')
In-Reply-To: <CAMCEyD75tSb33RkeN_==iLCWMcMLcQcHKPR=mgQB4Dc74c7Dnw@mail.gmail.com>
References: <CAMCEyD75tSb33RkeN_==iLCWMcMLcQcHKPR=mgQB4Dc74c7Dnw@mail.gmail.com>
Message-ID: <YZz2phTf4OHb7+XX@Dream-Machine1>

On 21/11/22 11:38PM, Alex Kleider wrote:
>
>Bob Stepp wrote:
>"""
>Do you have a system clipboard setup?? I had to get xsel going to use it with
>Neovim.
>
>Once you have a recognized (by Vim/Neovim) system clipboard configured, then
>you use the appropriate register(s).? In Vim/Neovim type ":h registers", which
>will describe them.? For instance if I have copied something to the system
>clipboard with the mouse and I am back in Vim/Neovim in insert mode I type
>"Ctrl-r, +" to paste it in.? If you are in normal mode you would use either
>"p" or "P" as you would with one of the alphabetic registers, but instead
>substitute "+".
>"""
>Thanks for your attempt to help, Bob, but I must confess to not understanding!
>I don't know of xsel or of Neovim...

xsel is one of a few *nix programs for interacting with the X server clipboard
selections.  It has nothing to do with the Vim/Neovim editors other than they
can make use of them.  You can Google for xsel or use your man pages for more
info.  Neovim is just a fork of Vim that so far retains compatibility with
Vim, so for most purposes Vim and Neovim are interchangeable.

>? ...I do have copy and paste working using just
>leftclick+C(opy or leftclick+Paste and am happy with that.
>I assume (but am not certain and for sure don't understand what the line is
>really doing) that the following line:
>" imap <C-v> <Esc>:set paste<CR>"+P :set nopaste<CR>a"
>in my .vimrc is providing me that functionality .
>Having said that, I did copy some of this text into the system clipboard and
>then while in insert mode in vim, "Ctrl-r, +" did accomplish a paste (the same
>as if I'd done 'leftclick, p'! )? That's good to know.

If this worked than you can forget about xsel.  Sounds like you did not have
to worry about the issues I originally had.

>How do you 'copy' a highlighted segment from vim into your system clipboard?

Just yank the selection into the "+" register just like you would yank text
into a lettered register.

Hope I'm clearer this time.  Must go to work!

BTW, you might want to Google or manpage xsel or whatever your system uses.  X
Server/X Windows has THREE selections it deals with: Primary, Secondary and
Clipboard.  It is useful to know the differences for both your mouse
functionality and using Vim and whatnot.

-- 
Wishing you only the best,
boB Stepp

"Human life begins of the far side of despair."
     -- Jean-Paul Sartre

From mats at wichmann.us  Tue Nov 23 09:39:05 2021
From: mats at wichmann.us (Mats Wichmann)
Date: Tue, 23 Nov 2021 07:39:05 -0700
Subject: [Tutor] Enable Python feature in vim editor
In-Reply-To: <855852f9-3481-2b87-4a4c-9108a90c4002@gmail.com>
References: <CAD7Ssm9OAqopu7fkF+Fjjy7A-2fVJLqbQ6bw3da1JMwe_SS9zw@mail.gmail.com>
 <855852f9-3481-2b87-4a4c-9108a90c4002@gmail.com>
Message-ID: <f7d4fe32-b260-9ce3-ba7e-676d1eefde5c@wichmann.us>

On 11/22/21 12:06, Leam Hall wrote:
> Hey Kaushal,
> 
> Here's part of my ~/.vimrc. You can do a lot with it, and there are 
> likely Python specific plugins.
> 
> ###
> set shiftwidth=2
> set shiftround
> set tabstop=4
> set softtabstop=4
> set noexpandtab
> set number
> set ruler
> set noautoindent
> set nosmartindent
> set noincsearch
> 
> syntax enable
> ###


those are some pretty odd settings...  for Python autoindent would seem 
more natural than noautoindent, and noexpandtab means tabs have the 
unfortunate opportunity to live in your edited content - you're pretty 
much agreeing to not use the tab key in Python coding in that case.

Curious how you came to these?


From k.d.jantzen at mailbox.org  Tue Nov 23 10:39:41 2021
From: k.d.jantzen at mailbox.org (Klaus Jantzen)
Date: Tue, 23 Nov 2021 16:39:41 +0100
Subject: [Tutor] Enable Python feature in vim editor
In-Reply-To: <CAD7Ssm9OAqopu7fkF+Fjjy7A-2fVJLqbQ6bw3da1JMwe_SS9zw@mail.gmail.com>
References: <CAD7Ssm9OAqopu7fkF+Fjjy7A-2fVJLqbQ6bw3da1JMwe_SS9zw@mail.gmail.com>
Message-ID: <f18d0d61-656a-85a1-8dbc-d4bae2c0f7ea@mailbox.org>

Hi,

in my .vimrc I have the following Python related entries:

============


au BufRead, BufNewFile *.py call SetPythonOptions()
function SetPythonOptions()
 ??? autocmd!
 ??? set tabstop=4
 ??? set softtabstop=4
 ??? set shiftwidth=4
 ??? " use spaces instead of tab
 ??? set expandtab
 ??? set autoindent
endfunction

" remove trailing blanks in Python files
au BufWritePre *.py %s/\s\+$//e

==============

K.D.J.

On 11/22/21 5:48 PM, Kaushal Shriyan wrote:
> Hi,
>
> I am using vim editor to write python scripts. Is there a way to enable
> syntax, help and indentation of python script?
>
> Thanks in advance. I look forward to hearing from you.
>
> Best Regards,
>
> Kaushal
> _______________________________________________
> Tutor maillist  -  Tutor at python.org
> To unsubscribe or change subscription options:
> https://mail.python.org/mailman/listinfo/tutor

From leamhall at gmail.com  Tue Nov 23 11:01:35 2021
From: leamhall at gmail.com (Leam Hall)
Date: Tue, 23 Nov 2021 10:01:35 -0600
Subject: [Tutor] Enable Python feature in vim editor
In-Reply-To: <f7d4fe32-b260-9ce3-ba7e-676d1eefde5c@wichmann.us>
References: <CAD7Ssm9OAqopu7fkF+Fjjy7A-2fVJLqbQ6bw3da1JMwe_SS9zw@mail.gmail.com>
 <855852f9-3481-2b87-4a4c-9108a90c4002@gmail.com>
 <f7d4fe32-b260-9ce3-ba7e-676d1eefde5c@wichmann.us>
Message-ID: <d9b75592-d78f-da42-64b6-b9b655969287@gmail.com>

On 11/23/21 08:39, Mats Wichmann wrote:
> On 11/22/21 12:06, Leam Hall wrote:
>> Hey Kaushal,
>>
>> Here's part of my ~/.vimrc. You can do a lot with it, and there are likely Python specific plugins.
> 
> those are some pretty odd settings...? for Python autoindent would seem more natural than noautoindent, and noexpandtab means tabs have the unfortunate opportunity to live in your edited content - you're pretty much agreeing to not use the tab key in Python coding in that case.
> 
> Curious how you came to these?

Hey Mats!

When I first learned Python, the "whitespace is significant" thing made a lot of sense. After that my shell, Perl, and Ruby code looked a lot like my Python.  :)  I've been on a Go phase for a bit, and those are Go settings, to match "go fmt". I'd agree though, for Python I prefer two spaces as indent, and no tabs in code at all.

Leam

-- 
Systems Programmer         (reuel.net/resume)
Scribe: The Domici War     (domiciwar.net)
General Ne'er-do-well      (github.com/LeamHall)

From tariqkhasiri at gmail.com  Tue Nov 23 06:51:52 2021
From: tariqkhasiri at gmail.com (Tariq Khasiri)
Date: Tue, 23 Nov 2021 17:51:52 +0600
Subject: [Tutor] code explanation
Message-ID: <CAFy_oHC2QfNbPThuZv5QTuMLECdkhFSQM2=5qGYHNAC7KS6u2Q@mail.gmail.com>

```
data = [[col, df[col].nunique()] for col in
df.columns.difference(["Reviews"])]
uniques = pd.DataFrame(data=data, columns=["columns", "num of unique
values"])

```

The first line is explaining the dataframe ( df) unique number of
elements in a column but i dont understand the the second half of the first
line of coding neither the second line of code. Can anyone help ?

From padowns at gmail.com  Tue Nov 23 13:04:51 2021
From: padowns at gmail.com (Peter Downs)
Date: Tue, 23 Nov 2021 10:04:51 -0800
Subject: [Tutor] Enable Python feature in vim editor
In-Reply-To: <f18d0d61-656a-85a1-8dbc-d4bae2c0f7ea@mailbox.org>
References: <CAD7Ssm9OAqopu7fkF+Fjjy7A-2fVJLqbQ6bw3da1JMwe_SS9zw@mail.gmail.com>
 <f18d0d61-656a-85a1-8dbc-d4bae2c0f7ea@mailbox.org>
Message-ID: <6e0e6524-7479-cf1f-0734-e53327434119@gmail.com>

Hey Klaus,

I like how you wrap the language specific settings in a function instead 
of having a bunch of separate autocmd lines like I do.

I also map function keys to tools like linters and the interpreter:

==8<==

autocmd BufNewFile,BufRead *.py nnoremap <buffer> <F5> :w<cr>:exec 
'!clear; pylint' shellescape(@%, 1)<cr>
autocmd BufNewFile,BufRead *.py nnoremap <buffer> <F6> :w<cr>:exec 
'!clear; pylama' shellescape(@%, 1)<cr>
autocmd BufNewFile,BufRead *.py nnoremap <buffer> <F9> :w<cr>:exec 
'!clear; python3' shellescape(@%, 1)<cr>

==8<==

that way you can test the code or check the syntax without leaving vim 
or switching windows.

Peter


On 11/23/21 7:39 AM, Klaus Jantzen via Tutor wrote:
> Hi,
>
> in my .vimrc I have the following Python related entries:
>
> ============
>
>
> au BufRead, BufNewFile *.py call SetPythonOptions()
> function SetPythonOptions()
> ??? autocmd!
> ??? set tabstop=4
> ??? set softtabstop=4
> ??? set shiftwidth=4
> ??? " use spaces instead of tab
> ??? set expandtab
> ??? set autoindent
> endfunction
>
> " remove trailing blanks in Python files
> au BufWritePre *.py %s/\s\+$//e
>
> ==============
>
> K.D.J.
>
> On 11/22/21 5:48 PM, Kaushal Shriyan wrote:
>> Hi,
>>
>> I am using vim editor to write python scripts. Is there a way to enable
>> syntax, help and indentation of python script?
>>
>> Thanks in advance. I look forward to hearing from you.
>>
>> Best Regards,
>>
>> Kaushal
>> _______________________________________________
>> Tutor maillist? -? Tutor at python.org
>> To unsubscribe or change subscription options:
>> https://mail.python.org/mailman/listinfo/tutor
> _______________________________________________
> Tutor maillist? -? Tutor at python.org
> To unsubscribe or change subscription options:
> https://mail.python.org/mailman/listinfo/tutor

From david at lowryduda.com  Tue Nov 23 14:30:10 2021
From: david at lowryduda.com (David Lowry-Duda)
Date: Tue, 23 Nov 2021 14:30:10 -0500
Subject: [Tutor] Enable Python feature in vim editor
In-Reply-To: <CAD7Ssm9OAqopu7fkF+Fjjy7A-2fVJLqbQ6bw3da1JMwe_SS9zw@mail.gmail.com>
References: <CAD7Ssm9OAqopu7fkF+Fjjy7A-2fVJLqbQ6bw3da1JMwe_SS9zw@mail.gmail.com>
Message-ID: <YZ1BQjswTxbGBr1X@icerm-dld>

On Mon, Nov 22, 2021 at 10:18:19PM +0530, Kaushal Shriyan wrote:
> I am using vim editor to write python scripts. Is there a way to 
> enable syntax, help and indentation of python script?

Welcome to the vim way! I also use vim as my primary python editor. I'll 
note that there has been a recent surge in power from language servers, 
and tools like vim-ale (https://github.com/dense-analysis/ale) or 
coc.nvim (https://github.com/neoclide/coc.nvim) [which I am led to 
believe works also for vim and not just neovim, but in fact I have not 
used it] might be very helpful. These enable various forms of 
autocompletion, definitions, signature help, mypy-type checking, and so 
on, from within vim.

I suggest that you consider these and whether or not you think they 
would be helpful in your setup.

And though it's actually quite old, I also recommend using some form of 
ctags for large projects, such as 
(https://github.com/universal-ctags/ctags). This facilitates quickly 
jumping to definitions, functions, and classes in a project.

- DLD

From cs at cskk.id.au  Tue Nov 23 17:30:05 2021
From: cs at cskk.id.au (Cameron Simpson)
Date: Wed, 24 Nov 2021 09:30:05 +1100
Subject: [Tutor] Enable Python feature in vim editor
In-Reply-To: <d9b75592-d78f-da42-64b6-b9b655969287@gmail.com>
References: <d9b75592-d78f-da42-64b6-b9b655969287@gmail.com>
Message-ID: <YZ1rbRKLf2Ed4n3m@cskk.homeip.net>

On 23Nov2021 10:01, Leam Hall <leamhall at gmail.com> wrote:
>When I first learned Python, the "whitespace is significant" thing made 
>a lot of sense. After that my shell, Perl, and Ruby code looked a lot 
>like my Python.  :)  I've been on a Go phase for a bit, and those are 
>Go settings, to match "go fmt". I'd agree though, for Python I prefer 
>two spaces as indent, and no tabs in code at all.

I've got quite a lot in my vi and vim settings, so I'll run through the 
things I've got which seem applicable to Python (and coding in general):

First my "vi" settings (sourced by my vimrc):

    set autoindent

Great for almost all coding; remember that at the start of a line ^D 
(ctrl-D) steps you backwards one indent step when you need to 
out-indent. I've got some autoindenting syntax stuff turned on too, so 
often I instead write the next line, let the auto stuff mangle the 
intended indent, and adjust with "<<" to left shift the line.

Oh, were you aware of the "<" and ">" keystrokes? Like many vim 
commands, followed by a cursor motion (or doubled to just affect the 
current line). So "<<" shifts the current line, "<}" shifts the lines 
from here the next empty line (great for shifting a whole code block), 
"20<<" shifts the next 20 lines including the current one, etc. It 
honours the "shiftwidth" setting below; mine is set to 2.

Note that having autoformatting (see below) reduces the need for this, 
but it is still very useful - I use it a lot. Including to indent the 
settings listing for this message!

    set autowrite

Writes the file when I switch to another, so switching files is just ":n 
filename". I pretty much always use revision control, so I am not very 
hung up on unwanted changes - a diff will always show them to me.

    set ignorecase

Just makes searching easier all around. Note that a mixed case search 
has a degree of case sensitivity anyway, so when you care about the case 
you can be more precise.

    " set nomesg
    set nowrapscan

I like to know when I've hit the last match instead of cycling to the 
top of the file - in a big file that isn't always obvious.

    set showmatch

Bounces the cursor to the matching bracket when you type a closing 
bracket, and also highlights the starting bracking. Quite ahndy.

    set shiftwidth=2

Doesn't everyone indent (and therefore shift) by 2 spaces?

    " set tabstop=8
    set tabstop=4

Not too big, not too small. I use expandtabs, so I don't embed TABs in 
my code.

    set noterse
    set writeany

Goes with autowrite.

    map! \c cs at cskk.id.au
    map! \C Cameron Simpson <\c>

Handy for writing my email address.

    " Markdown: `code` a word
    map `` lbi`ea`

I write MarkDown docstrings and like MarkDown in general for a lot of 
simple doco. This defines a `` macro to put backticks around the current 
word, very handy for embedding "computer names" in text.

    map!  :stop
a
    map! 
 
a
    map!  i
    map!  lli
    map! 
 I

Suspend (^Z) and some emacs-like cursor motions. The suspend is pretty 
ancient, I think that works transparently in vim these days. And I 
rarely suspend in a multiwindow/multitab/multipane environment.

    map # :n #
z.

So handy. Switch between this file and the previous with a single 
keystroke.

    map g Gz.

I find typing an uppercase G to go to a line tiresome.

    map t :ta 

"t" shorthand for :td (go to tag). I use tagfiles agressively, and they 
work well in Python. Note that ctags also makes tags for filenames, so 
finding a source file in a large hierarchy is also much easier. I've got 
a couple of shell scripts to make regenerating tags files easier too:

    https://hg.sr.ht/~cameron-simpson/css/browse/bin/ctags-update

and a shell function "uptags" to run it:

    uptags () {
         >> tags
         ctags-update -o tags ${1+"$@"}
         ls -ld tags
     }

Note in particular the ctags options I use at the bottom of 
"ctags-update".

Then the vim settings:

    source ~/rc/vi

Of course.

    set encoding=utf-8
    scriptencoding utf-8

This is the way.

    set bg=dark
    colorscheme cameron
    syntax reset
    syntax on

Colours.

    set autoread

See and load the file if it is not modified and the original changes.  
This means I can have multiple vims watching the same file. I 
reflexively save quite often (and autosave above does it a lot too) so 
my buffers are usually unmodified.

    set backupcopy=yes

I write in place (hard link paranoia) so a backup is handy during 
rewrites.

    set clipboard=autoselect

Doesn't work as well as I've like.

    set cursorline

I find it useful to highlight the current line - I've usualy got at 
least 2 buffers visible so this aids not losing track.

    set expandtab

Of course. I sometimes like TABs to typing an indent, but not for the 
text itself, which should have spaces.

    set fileformats=unix,mac,dos

Just cope and don't mangle things.

    set ignorecase
    set incsearch

Nicer searching.

    set list
    set listchars=tab:?\ ,trail:_,extends:>,precedes:<,conceal:*

Stuff I like visible in "list" mode.

    set mouse=
    set mousefocus=on
    set mousehide
    set mousemodel=extend

What I've landed on for mouse integration. I found the other modes 
either annoying or not working seamlessly. In particular I like to 
GUI-level copy/paste with the mouse and mouse integration broke that 
just for the vim windows, so annoying.

    set nofsync

Overuse of fsync is just bad.

    set scrolloff=2

2 lines of text visible at the top/bottom of the screen WRT to the 
cursor line.

    set smartcase

I think this is the clever "mixed case searches are case senstivie" 
thing.

    set t_Co=256

I've got a 256 colour terminal emulator (IIRC).

    set ttyfast

An ancient setting I think.

    set updatetime=2000

Polling interval for external changes?

    set wildignore+=*.swp,*.zip,*.exe,*.a,*.o,*.pyc
    set wildmenu wildmode=list:longest

Files to ignore when autocompleting filenames.

    map <C-W><C-T> :split %<CR>
    map <C-W><C-N> :new<CR>:n 

"vim window mode", so useful. I use ^W^T to do a horizontal split 
(matches with Cmd-Shift-T in iTerm to do that same with panes), ^W^V for 
a vertical split (atches with Cmd-Shift-V in iTerm). I've got similar 
bindings in tmux, too.

    map ,f :silent !format %



The big winner. Macro to autoformat this file using a code formatter.  
The "format" script is my own, here:

    https://hg.sr.ht/~cameron-simpson/css/browse/bin-cs/format

which runs my preferred formatter (language specific) on the file. See 
the script for details, write your own! Or adopt and adapt!

    autocmd CursorHold * checktime | call feedkeys("")
    autocmd FocusGained,BufEnter * :checktime

These are tickers to drive the automatic detection of external changes.  
So useful!

    " Remove ALL autocommands for the current group.
    " autocmd!
    autocmd BufWritePost *.go :silent !echo; format -t .autoformat %
    autocmd BufWritePost *.php :silent !echo; format -t .autoformat %
    autocmd BufWritePost *.js :silent !echo; format -t .autoformat %
    autocmd BufWritePost *.py :silent !echo; format -t .autoformat %

This automatically autoformats various file extensions on save, _if_ the 
source tree has a nonempty ".autoformat" file in it. So I go:

    echo 1 >.autoformat

in my code tree and off we go! There are trees where you don't want 
magic autoformatting, particularly existing codebases where you don't 
want autoformat noise in your commits.

    let @t=system('tags=$(findup tags) || tags=tags; echo "set tags=$tags"')
    @t

Set the "tags" vi/vim setting if you've just made a fresh tags file.

    autocmd BufWritePost * :let @t=system('vim-ctags-update ' . shellescape(@%))
    autocmd BufWritePost * :@t
    autocmd BufWritePost * :redraw!

Update the tags when you save a file.

    autocmd BufRead,BufNewFile haproxy* set ft=haproxy

Recognise an addition file syntax based on filename.

    if has("gui_macvim")
      set macthinstrokes
    endif

Setting for GUI Vim on a Mac, I never use it.

Cheers,
Cameron Simpson <cs at cskk.id.au>

From leamhall at gmail.com  Tue Nov 23 21:07:05 2021
From: leamhall at gmail.com (Leam Hall)
Date: Tue, 23 Nov 2021 20:07:05 -0600
Subject: [Tutor] Enable Python feature in vim editor
In-Reply-To: <YZ1rbRKLf2Ed4n3m@cskk.homeip.net>
References: <d9b75592-d78f-da42-64b6-b9b655969287@gmail.com>
 <YZ1rbRKLf2Ed4n3m@cskk.homeip.net>
Message-ID: <1607f623-4125-bdc9-251c-0e78cc282a21@gmail.com>

On 11/23/21 16:30, Cameron Simpson wrote:

...
     A lot of cool stuff.
...

Seriously, man, you need to write that in a tutorial!

Leam

-- 
Systems Programmer         (reuel.net/resume)
Scribe: The Domici War     (domiciwar.net)
General Ne'er-do-well      (github.com/LeamHall)

From alexkleider at gmail.com  Wed Nov 24 12:00:00 2021
From: alexkleider at gmail.com (Alex Kleider)
Date: Wed, 24 Nov 2021 09:00:00 -0800
Subject: [Tutor] Enable Python feature in vim editor
In-Reply-To: <1607f623-4125-bdc9-251c-0e78cc282a21@gmail.com>
References: <d9b75592-d78f-da42-64b6-b9b655969287@gmail.com>
 <YZ1rbRKLf2Ed4n3m@cskk.homeip.net>
 <1607f623-4125-bdc9-251c-0e78cc282a21@gmail.com>
Message-ID: <CAMCEyD7-9E_EutuT4fpA9=p-gEpUxFw_fVBpvvP3=s7XNoOCMA@mail.gmail.com>

On Tue, Nov 23, 2021 at 6:08 PM Leam Hall <leamhall at gmail.com> wrote:

> On 11/23/21 16:30, Cameron Simpson wrote:
>
> ...
>      A lot of cool stuff.
> ...
>
> Seriously, man, you need to write that in a tutorial!
>
> Leam
>
>
++

I for one would certainly be interested in such a write up (especially if
it was flushed out a bit so I could more fully understand the code.)

> --
> Systems Programmer         (reuel.net/resume)
> Scribe: The Domici War     (domiciwar.net)
> General Ne'er-do-well      (github.com/LeamHall)
> _______________________________________________
> Tutor maillist  -  Tutor at python.org
> To unsubscribe or change subscription options:
> https://mail.python.org/mailman/listinfo/tutor
>

From kaushalshriyan at gmail.com  Wed Nov 24 12:15:48 2021
From: kaushalshriyan at gmail.com (Kaushal Shriyan)
Date: Wed, 24 Nov 2021 22:45:48 +0530
Subject: [Tutor] Enable Python feature in vim editor
In-Reply-To: <CAMCEyD7-9E_EutuT4fpA9=p-gEpUxFw_fVBpvvP3=s7XNoOCMA@mail.gmail.com>
References: <d9b75592-d78f-da42-64b6-b9b655969287@gmail.com>
 <YZ1rbRKLf2Ed4n3m@cskk.homeip.net>
 <1607f623-4125-bdc9-251c-0e78cc282a21@gmail.com>
 <CAMCEyD7-9E_EutuT4fpA9=p-gEpUxFw_fVBpvvP3=s7XNoOCMA@mail.gmail.com>
Message-ID: <CAD7Ssm_V7wec-tRMWB5AZrbZXUydwvxpCaem6x-0OgqrcV_50w@mail.gmail.com>

On Wed, Nov 24, 2021 at 10:30 PM Alex Kleider <alexkleider at gmail.com> wrote:

> On Tue, Nov 23, 2021 at 6:08 PM Leam Hall <leamhall at gmail.com> wrote:
>
> > On 11/23/21 16:30, Cameron Simpson wrote:
> >
> > ...
> >      A lot of cool stuff.
> > ...
> >
> > Seriously, man, you need to write that in a tutorial!
> >
> > Leam
> >
> >
> ++
>
> I for one would certainly be interested in such a write up (especially if
> it was flushed out a bit so I could more fully understand the code.)
>
> > --
> > Systems Programmer         (reuel.net/resume)
> > Scribe: The Domici War     (domiciwar.net)
> > General Ne'er-do-well      (github.com/LeamHall)
> > _______________________________________________
> > Tutor maillist  -  Tutor at python.org
> > To unsubscribe or change subscription options:
> > https://mail.python.org/mailman/listinfo/tutor
> >
> _______________________________________________
> Tutor maillist  -  Tutor at python.org
> To unsubscribe or change subscription options:
> https://mail.python.org/mailman/listinfo/tutor


Hi,

I am running CentOS Linux release 7.9.2009 (Core) and have enabled below
entry in .vimrc file

$cat .vimrc
set shiftwidth=2
set shiftround
set tabstop=4
set softtabstop=4
set noexpandtab
set number
set ruler
set noautoindent
set nosmartindent
set noincsearch
syntax enable
$

when i do vim testpythonscript.py I am facing the below Pymode error

$vim testpythonscript.py

[Pymode]: error: Pymode requires vim compiled with +python3 (exclusively).
Most of features will be disabled.
                                    0,0-1         All

$vim --version
VIM - Vi IMproved 7.4 (2013 Aug 10, compiled Dec 15 2020 16:44:08)
Included patches: 1-207, 209-629
Modified by <bugzilla at redhat.com>
Compiled by <bugzilla at redhat.com>
Huge version without GUI.  Features included (+) or not (-):
+acl             +farsi           +mouse_netterm   +syntax
+arabic          +file_in_path    +mouse_sgr       +tag_binary
+autocmd         +find_in_path    -mouse_sysmouse  +tag_old_static
-balloon_eval    +float           +mouse_urxvt     -tag_any_white
-browse          +folding         +mouse_xterm     -tcl
++builtin_terms  -footer          +multi_byte      +terminfo
+byte_offset     +fork()          +multi_lang      +termresponse
+cindent         +gettext         -mzscheme        +textobjects
-clientserver    -hangul_input    +netbeans_intg   +title
-clipboard       +iconv           +path_extra      -toolbar
+cmdline_compl   +insert_expand   +perl            +user_commands
+cmdline_hist    +jumplist        +persistent_undo +vertsplit
+cmdline_info    +keymap          +postscript      +virtualedit
+comments        +langmap         +printer         +visual
+conceal         +libcall         +profile         +visualextra
+cryptv          +linebreak       +python/dyn      +viminfo
+cscope          +lispindent      -python3         +vreplace
+cursorbind      +listcmds        +quickfix        +wildignore
+cursorshape     +localmap        +reltime         +wildmenu
+dialog_con      -lua             +rightleft       +windows
+diff            +menu            +ruby/dyn        +writebackup
+digraphs        +mksession       +scrollbind      -X11
-dnd             +modify_fname    +signs           -xfontset
-ebcdic          +mouse           +smartindent     -xim
+emacs_tags      -mouseshape      -sniff           -xsmp
+eval            +mouse_dec       +startuptime     -xterm_clipboard
+ex_extra        +mouse_gpm       +statusline      -xterm_save
+extra_search    -mouse_jsbterm   -sun_workshop    -xpm
   system vimrc file: "/etc/vimrc"
     user vimrc file: "$HOME/.vimrc"
 2nd user vimrc file: "~/.vim/vimrc"
      user exrc file: "$HOME/.exrc"
  fall-back for $VIM: "/etc"
 f-b for $VIMRUNTIME: "/usr/share/vim/vim74"
Compilation: gcc -c -I. -Iproto -DHAVE_CONFIG_H     -O2 -g -pipe -Wall
-fexceptions -fstack-protector-strong --param=ssp-buffer-size=4
-grecord-gcc-switches   -m64 -mtune=generic -D_GNU_SOURCE
-D_FILE_OFFSET_BITS=64 -D__linux__ -D_REENTRANT -U_FORTIFY_SOURCE
-D_FORTIFY_SOURCE=1
Linking: gcc   -L. -Wl,-z,relro -fstack-protector -rdynamic
-Wl,-export-dynamic -Wl,--enable-new-dtags -Wl,-rpath,/usr/lib64/perl5/CORE
 -Wl,-z,relro  -L/usr/local/lib -Wl,--as-needed -o vim        -lm -lnsl
 -lselinux  -lncurses -lacl -lattr -lgpm -ldl   -Wl,--enable-new-dtags
-Wl,-rpath,/usr/lib64/perl5/CORE  -fstack-protector
 -L/usr/lib64/perl5/CORE -lperl -lresolv -lnsl -ldl -lm -lcrypt -lutil
-lpthread -lc
#

Please guide. Thanks in advance.

Best Regards,

Kaushal

From marjababernard at gmail.com  Wed Nov 24 15:17:15 2021
From: marjababernard at gmail.com (Bernard Marjaba)
Date: Wed, 24 Nov 2021 15:17:15 -0500
Subject: [Tutor] Error When Using CoolProp
Message-ID: <A6BACFB5-DEDD-47E4-8092-F42C1028A72B@gmail.com>

Hello

I am having trouble using CoolProp with python. I have macOS Big Sur 11.5.1 with python version 3.10.

import CoolProp.CoolProp as CP
is giving me the error ModuleNotFoundError: No module named ?CoolProp.CoolProp? because it is not installed. I am however using it with MATLAB with no issues. I assume each software has its own wrapper?

So I tried installing CoolProp using pip install coolprop, and got the following error:

Collecting coolprop
  Using cached CoolProp-6.4.1.tar.gz (12.9 MB)
  Preparing metadata (setup.py) ... done
Using legacy 'setup.py install' for coolprop, since package 'wheel' is not installed.
Installing collected packages: coolprop
    Running setup.py install for coolprop ... error
    ERROR: Command errored out with exit status 1:
     command: '/Users/Bernard/PycharmProjects/Isentropic SUS Model/venv/bin/python' -u -c 'import io, os, sys, setuptools, tokenize; sys.argv[0] = '"'"'/private/var/folders/1j/jv39r0t12cb4dhscxkdz97740000gn/T/pip-install-z5afcrzx/coolprop_6739af7137474652994855ae32a03dd4/setup.py'"'"'; __file__='"'"'/private/var/folders/1j/jv39r0t12cb4dhscxkdz97740000gn/T/pip-install-z5afcrzx/coolprop_6739af7137474652994855ae32a03dd4/setup.py'"'"';f = getattr(tokenize, '"'"'open'"'"', open)(__file__) if os.path.exists(__file__) else io.StringIO('"'"'from setuptools import setup; setup()'"'"');code = f.read().replace('"'"'\r\n'"'"', '"'"'\n'"'"');f.close();exec(compile(code, __file__, '"'"'exec'"'"'))' install --record /private/var/folders/1j/jv39r0t12cb4dhscxkdz97740000gn/T/pip-record-8453i4i7/install-record.txt --single-version-externally-managed --compile --install-headers '/Users/Bernard/PycharmProjects/Isentropic SUS Model/venv/include/site/python3.9/coolprop'
         cwd: /private/var/folders/1j/jv39r0t12cb4dhscxkdz97740000gn/T/pip-install-z5afcrzx/coolprop_6739af7137474652994855ae32a03dd4/
    Complete output (79 lines):
    xcrun: error: invalid active developer path (/Library/Developer/CommandLineTools), missing xcrun at: /Library/Developer/CommandLineTools/usr/bin/xcrun
    OSX build detected, targetting 10.9 using clang/gcc v0.0.
    Cython will not be used; cy_ext is cpp
    running install
    /Users/Bernard/PycharmProjects/Isentropic SUS Model/venv/lib/python3.9/site-packages/setuptools/command/install.py:34: SetuptoolsDeprecationWarning: setup.py install is deprecated. Use build and pip and other standards-based tools.
      warnings.warn(
    running build
    running build_py
    creating build
    creating build/lib.macosx-10.9-x86_64-3.9
    creating build/lib.macosx-10.9-x86_64-3.9/CoolProp
    copying CoolProp/constants.py -> build/lib.macosx-10.9-x86_64-3.9/CoolProp
    copying CoolProp/__init__.py -> build/lib.macosx-10.9-x86_64-3.9/CoolProp
    copying CoolProp/BibtexParser.py -> build/lib.macosx-10.9-x86_64-3.9/CoolProp
    copying CoolProp/HumidAirProp.py -> build/lib.macosx-10.9-x86_64-3.9/CoolProp
    copying CoolProp/State.py -> build/lib.macosx-10.9-x86_64-3.9/CoolProp
    creating build/lib.macosx-10.9-x86_64-3.9/CoolProp/tests
    copying CoolProp/tests/runner.py -> build/lib.macosx-10.9-x86_64-3.9/CoolProp/tests
    copying CoolProp/tests/test_plots.py -> build/lib.macosx-10.9-x86_64-3.9/CoolProp/tests
    copying CoolProp/tests/test_Props.py -> build/lib.macosx-10.9-x86_64-3.9/CoolProp/tests
    copying CoolProp/tests/__init__.py -> build/lib.macosx-10.9-x86_64-3.9/CoolProp/tests
    copying CoolProp/tests/test_CoolPropState.py -> build/lib.macosx-10.9-x86_64-3.9/CoolProp/tests
    creating build/lib.macosx-10.9-x86_64-3.9/CoolProp/GUI
    copying CoolProp/GUI/__init__.py -> build/lib.macosx-10.9-x86_64-3.9/CoolProp/GUI
    copying CoolProp/GUI/CoolPropGUI.py -> build/lib.macosx-10.9-x86_64-3.9/CoolProp/GUI
    copying CoolProp/GUI/PsychScript.py -> build/lib.macosx-10.9-x86_64-3.9/CoolProp/GUI
    creating build/lib.macosx-10.9-x86_64-3.9/CoolProp/Plots
    copying CoolProp/Plots/ConsistencyPlots_pcsaft.py -> build/lib.macosx-10.9-x86_64-3.9/CoolProp/Plots
    copying CoolProp/Plots/PsychChart.py -> build/lib.macosx-10.9-x86_64-3.9/CoolProp/Plots
    copying CoolProp/Plots/SimpleCycles.py -> build/lib.macosx-10.9-x86_64-3.9/CoolProp/Plots
    copying CoolProp/Plots/__init__.py -> build/lib.macosx-10.9-x86_64-3.9/CoolProp/Plots
    copying CoolProp/Plots/psy.py -> build/lib.macosx-10.9-x86_64-3.9/CoolProp/Plots
    copying CoolProp/Plots/Plots.py -> build/lib.macosx-10.9-x86_64-3.9/CoolProp/Plots
    copying CoolProp/Plots/Common.py -> build/lib.macosx-10.9-x86_64-3.9/CoolProp/Plots
    copying CoolProp/Plots/SimpleCyclesCompression.py -> build/lib.macosx-10.9-x86_64-3.9/CoolProp/Plots
    copying CoolProp/Plots/ConsistencyPlots.py -> build/lib.macosx-10.9-x86_64-3.9/CoolProp/Plots
    copying CoolProp/Plots/PsychScript.py -> build/lib.macosx-10.9-x86_64-3.9/CoolProp/Plots
    copying CoolProp/Plots/Tests.py -> build/lib.macosx-10.9-x86_64-3.9/CoolProp/Plots
    copying CoolProp/Plots/SimpleCyclesExpansion.py -> build/lib.macosx-10.9-x86_64-3.9/CoolProp/Plots
    copying CoolProp/typedefs.pxd -> build/lib.macosx-10.9-x86_64-3.9/CoolProp
    copying CoolProp/CoolProp.pxd -> build/lib.macosx-10.9-x86_64-3.9/CoolProp
    copying CoolProp/State.pxd -> build/lib.macosx-10.9-x86_64-3.9/CoolProp
    copying CoolProp/cAbstractState.pxd -> build/lib.macosx-10.9-x86_64-3.9/CoolProp
    copying CoolProp/constants_header.pxd -> build/lib.macosx-10.9-x86_64-3.9/CoolProp
    copying CoolProp/AbstractState.pxd -> build/lib.macosx-10.9-x86_64-3.9/CoolProp
    copying CoolProp/Plots/psyrc -> build/lib.macosx-10.9-x86_64-3.9/CoolProp/Plots
    running build_ext
    creating private
    creating private/var
    creating private/var/folders
    creating private/var/folders/1j
    creating private/var/folders/1j/jv39r0t12cb4dhscxkdz97740000gn
    creating private/var/folders/1j/jv39r0t12cb4dhscxkdz97740000gn/T
    creating private/var/folders/1j/jv39r0t12cb4dhscxkdz97740000gn/T/pip-install-z5afcrzx
    creating private/var/folders/1j/jv39r0t12cb4dhscxkdz97740000gn/T/pip-install-z5afcrzx/coolprop_6739af7137474652994855ae32a03dd4
    gcc -Wno-unused-result -Wsign-compare -Wunreachable-code -fno-common -dynamic -DNDEBUG -g -fwrapv -O3 -Wall -arch x86_64 -g -I/Users/Bernard/PycharmProjects/Isentropic SUS Model/venv/include -I/Library/Frameworks/Python.framework/Versions/3.9/include/python3.9 -c /private/var/folders/1j/jv39r0t12cb4dhscxkdz97740000gn/T/pip-install-z5afcrzx/coolprop_6739af7137474652994855ae32a03dd4/tmp0hdk2tsu.cpp -o private/var/folders/1j/jv39r0t12cb4dhscxkdz97740000gn/T/pip-install-z5afcrzx/coolprop_6739af7137474652994855ae32a03dd4/tmp0hdk2tsu.o
    xcrun: error: invalid active developer path (/Library/Developer/CommandLineTools), missing xcrun at: /Library/Developer/CommandLineTools/usr/bin/xcrun
    gcc -Wno-unused-result -Wsign-compare -Wunreachable-code -fno-common -dynamic -DNDEBUG -g -fwrapv -O3 -Wall -arch x86_64 -g -I/Users/Bernard/PycharmProjects/Isentropic SUS Model/venv/include -I/Library/Frameworks/Python.framework/Versions/3.9/include/python3.9 -c /private/var/folders/1j/jv39r0t12cb4dhscxkdz97740000gn/T/pip-install-z5afcrzx/coolprop_6739af7137474652994855ae32a03dd4/tmp0r3vfej0.cpp -o private/var/folders/1j/jv39r0t12cb4dhscxkdz97740000gn/T/pip-install-z5afcrzx/coolprop_6739af7137474652994855ae32a03dd4/tmp0r3vfej0.o
    xcrun: error: invalid active developer path (/Library/Developer/CommandLineTools), missing xcrun at: /Library/Developer/CommandLineTools/usr/bin/xcrun
    gcc -Wno-unused-result -Wsign-compare -Wunreachable-code -fno-common -dynamic -DNDEBUG -g -fwrapv -O3 -Wall -arch x86_64 -g -I/Users/Bernard/PycharmProjects/Isentropic SUS Model/venv/include -I/Library/Frameworks/Python.framework/Versions/3.9/include/python3.9 -c /private/var/folders/1j/jv39r0t12cb4dhscxkdz97740000gn/T/pip-install-z5afcrzx/coolprop_6739af7137474652994855ae32a03dd4/tmp93394q_4.cpp -o private/var/folders/1j/jv39r0t12cb4dhscxkdz97740000gn/T/pip-install-z5afcrzx/coolprop_6739af7137474652994855ae32a03dd4/tmp93394q_4.o
    xcrun: error: invalid active developer path (/Library/Developer/CommandLineTools), missing xcrun at: /Library/Developer/CommandLineTools/usr/bin/xcrun
    Adding these shared_ptr compilation macros: []
    building 'CoolProp.CoolProp' extension
    creating build/temp.macosx-10.9-x86_64-3.9
    creating build/temp.macosx-10.9-x86_64-3.9/CoolProp
    creating build/temp.macosx-10.9-x86_64-3.9/src
    creating build/temp.macosx-10.9-x86_64-3.9/src/Backends
    creating build/temp.macosx-10.9-x86_64-3.9/src/Backends/Cubics
    creating build/temp.macosx-10.9-x86_64-3.9/src/Backends/Helmholtz
    creating build/temp.macosx-10.9-x86_64-3.9/src/Backends/Helmholtz/Fluids
    creating build/temp.macosx-10.9-x86_64-3.9/src/Backends/IF97
    creating build/temp.macosx-10.9-x86_64-3.9/src/Backends/Incompressible
    creating build/temp.macosx-10.9-x86_64-3.9/src/Backends/PCSAFT
    creating build/temp.macosx-10.9-x86_64-3.9/src/Backends/REFPROP
    creating build/temp.macosx-10.9-x86_64-3.9/src/Backends/Tabular
    creating build/temp.macosx-10.9-x86_64-3.9/src/Tests
    gcc -Wno-unused-result -Wsign-compare -Wunreachable-code -fno-common -dynamic -DNDEBUG -g -fwrapv -O3 -Wall -arch x86_64 -g -I. -I./include -I./src -I./externals/Eigen -I./externals/fmtlib -I./externals/msgpack-c/include -I/Users/Bernard/PycharmProjects/Isentropic SUS Model/venv/include -I/Library/Frameworks/Python.framework/Versions/3.9/include/python3.9 -c CoolProp/CoolProp.cpp -o build/temp.macosx-10.9-x86_64-3.9/CoolProp/CoolProp.o
    xcrun: error: invalid active developer path (/Library/Developer/CommandLineTools), missing xcrun at: /Library/Developer/CommandLineTools/usr/bin/xcrun
    error: command '/usr/bin/gcc' failed with exit code 1
    ----------------------------------------
ERROR: Command errored out with exit status 1: '/Users/Bernard/PycharmProjects/Isentropic SUS Model/venv/bin/python' -u -c 'import io, os, sys, setuptools, tokenize; sys.argv[0] = '"'"'/private/var/folders/1j/jv39r0t12cb4dhscxkdz97740000gn/T/pip-install-z5afcrzx/coolprop_6739af7137474652994855ae32a03dd4/setup.py'"'"'; __file__='"'"'/private/var/folders/1j/jv39r0t12cb4dhscxkdz97740000gn/T/pip-install-z5afcrzx/coolprop_6739af7137474652994855ae32a03dd4/setup.py'"'"';f = getattr(tokenize, '"'"'open'"'"', open)(__file__) if os.path.exists(__file__) else io.StringIO('"'"'from setuptools import setup; setup()'"'"');code = f.read().replace('"'"'\r\n'"'"', '"'"'\n'"'"');f.close();exec(compile(code, __file__, '"'"'exec'"'"'))' install --record /private/var/folders/1j/jv39r0t12cb4dhscxkdz97740000gn/T/pip-record-8453i4i7/install-record.txt --single-version-externally-managed --compile --install-headers '/Users/Bernard/PycharmProjects/Isentropic SUS Model/venv/include/site/python3.9/coolprop' Check the logs for full command output.
 

Thanks and regards,
Bernard Marjaba
(514) 922-9807


From alan.gauld at yahoo.co.uk  Thu Nov 25 03:52:01 2021
From: alan.gauld at yahoo.co.uk (Alan Gauld)
Date: Thu, 25 Nov 2021 08:52:01 +0000
Subject: [Tutor] code explanation
In-Reply-To: <CAFy_oHC2QfNbPThuZv5QTuMLECdkhFSQM2=5qGYHNAC7KS6u2Q@mail.gmail.com>
References: <CAFy_oHC2QfNbPThuZv5QTuMLECdkhFSQM2=5qGYHNAC7KS6u2Q@mail.gmail.com>
Message-ID: <snnirh$a4l$1@ciao.gmane.io>

On 23/11/2021 11:51, Tariq Khasiri wrote:
> ```
> data = [[col, df[col].nunique()] for col in
> df.columns.difference(["Reviews"])]
> uniques = pd.DataFrame(data=data, columns=["columns", "num of unique
> values"])
> 
> ```
> 
> The first line is explaining the dataframe ( df) unique number of
> elements in a column but i dont understand the the second half of the first
> line of coding neither the second line of code. Can anyone help ?

I'm not sure what aspect you don't understand so I'll start by stating
that the first two lines of code are a single line of Python split for
readability. I'll simplify it so that it can be seen on a single line:

func1 = df[0].nunique  #0 is arbitrary, assumes all items of same type
func2 = df.columns.difference

data = [[cl, func()] for cl in func2(["Reviews"])]

So the line is a list comprehension making use of two functions.

If that is not what was confusing you please repost with more specifics.

-- 
Alan G
Author of the Learn to Program web site
http://www.alan-g.me.uk/
http://www.amazon.com/author/alan_gauld
Follow my photo-blog on Flickr at:
http://www.flickr.com/photos/alangauldphotos



From alan.gauld at yahoo.co.uk  Thu Nov 25 03:58:13 2021
From: alan.gauld at yahoo.co.uk (Alan Gauld)
Date: Thu, 25 Nov 2021 08:58:13 +0000
Subject: [Tutor] Error When Using CoolProp
In-Reply-To: <A6BACFB5-DEDD-47E4-8092-F42C1028A72B@gmail.com>
References: <A6BACFB5-DEDD-47E4-8092-F42C1028A72B@gmail.com>
Message-ID: <snnj75$n0$1@ciao.gmane.io>

On 24/11/2021 20:17, Bernard Marjaba wrote:
> Hello
> 
> I am having trouble using CoolProp with python. I have macOS Big Sur 11.5.1 with python version 3.10.
> 
> import CoolProp.CoolProp as CP
> is giving me the error ModuleNotFoundError: No module named ?CoolProp.CoolProp? because it is not installed. I am however using it with MATLAB with no issues. I assume each software has its own wrapper?

I've never heard of coolprop but, in general, binary packages
will have separate wrappers for each application that uses them,
so Python and Matlab will each need their own wrapper.

As to what's going wrong with the pip I have no idea.
Are you using a virtual environment?
Are you calling pip directly or using "python -m pip..."

Perhaps somebody else can respond. Or you might like to
post on any coolprop support fora.

>     Running setup.py install for coolprop ... error
>     ERROR: Command errored out with exit status 1:

-- 
Alan G
Author of the Learn to Program web site
http://www.alan-g.me.uk/
http://www.amazon.com/author/alan_gauld
Follow my photo-blog on Flickr at:
http://www.flickr.com/photos/alangauldphotos



From manpritsinghece at gmail.com  Fri Nov 26 11:06:08 2021
From: manpritsinghece at gmail.com (Manprit Singh)
Date: Fri, 26 Nov 2021 21:36:08 +0530
Subject: [Tutor] Using super() in classes
Message-ID: <CAO1OCwY3xnG72QTW-vpsRsFGwE-BT7M_HTdajrftDposSeicQA@mail.gmail.com>

Dear sir,

Consider the below given examples :

class ABC:
    def show(self):
        print("HELLO")

class ABCD(ABC):
    def show(self):
        print("HI")
        super().show()

obj = ABCD()
obj.show()
will give output as :

HI
HELLO

Which is my desired output, here i have used super() inside class ABCD, so

that I can call show() of class ABC inside ABCD. Here If I write self.show()

instead of super().show(), it will call show() of class ABCD and it will

proceed like a recursive function .

Just need to know if my explanation is correct or not . Secondarily
the above given

given example can be written in the below written way or not ? Here instead

of writing super().show() in class ABCD i have written ABC.show(self) .According

to me it will serve the same purpose as that of the above written classes.

Am I correct ?


class ABC:
    def show(self):
        print("HELLO")

class ABCD(ABC):
    def show(self):
        print("HI")
        ABC.show(self)

obj = ABCD()
obj.show()

My second Example where i am calling show() of parent class inside a method of

child class whose name is not show(), but child class has a method with

name show, You can see i have called show() of parent class by writing

super().show() inside the greeting method of child class . It it ok to
do like this ?


class ABC:
    def show(self):
        print("HELLO")

class ABCD(ABC):
    def show(self):
        print("HI")

    def greeting(self, Name):
        super().show()
        print(Name)

obj = ABCD()
obj.greeting("Ravi")

Which gives the desired output as below:

HELLO
Ravi

Kindly guidr

From alan.gauld at yahoo.co.uk  Fri Nov 26 11:52:37 2021
From: alan.gauld at yahoo.co.uk (Alan Gauld)
Date: Fri, 26 Nov 2021 16:52:37 +0000
Subject: [Tutor] Using super() in classes
In-Reply-To: <CAO1OCwY3xnG72QTW-vpsRsFGwE-BT7M_HTdajrftDposSeicQA@mail.gmail.com>
References: <CAO1OCwY3xnG72QTW-vpsRsFGwE-BT7M_HTdajrftDposSeicQA@mail.gmail.com>
Message-ID: <snr3cm$c46$1@ciao.gmane.io>

On 26/11/2021 16:06, Manprit Singh wrote:

> class ABC:
>     def show(self):
>         print("HELLO")
> 
> class ABCD(ABC):
>     def show(self):
>         print("HI")
>         super().show()
> 
> obj = ABCD()
> obj.show()

> Just need to know if my explanation is correct or not .

Yes, all good so far.

> given example can be written in the below written way or not ? Here instead
> of writing super().show() in class ABCD i have written ABC.show(self) .According
> to me it will serve the same purpose as that of the above written classes.
> 
> Am I correct ?

In the case of single inheritance 9ie only one superclass) yes.
And that is how most Python code prior to v3 was written. And
for single inheritance, often still is.

But for multiple inheritance super() may behave differently, especially
when you have inheritance "diamonds" at work. eg

class A; pass
class B(A): pass
class C(A): pass
class D(B,C) : pass

Now in the init of D you have the choice of calling B.init, C.init,
super().init.

And since both B and C inherit from A how often should A.init
be called and when?

super is designed to resolve those issues.

As an experiment try it with print() methods as you did above
to show which class is which. See if you find a difference.

The other case to consider is what happens if only one of B or C
implements a method that is implemented by A.
Now you decide override that method in D.
How do you get all 3 methods called?

What if you have multiple levels of inheritance - 3 or 4 deep say?

It all starts to get very complicated if you need to track back
to find which superclass gets called for which method.

> 
> class ABCD(ABC):
>     def show(self):
>         print("HI")
> 
>     def greeting(self, Name):
>         super().show()
>         print(Name)

Not only OK but the preferred way to do it.

-- 
Alan G
Author of the Learn to Program web site
http://www.alan-g.me.uk/
http://www.amazon.com/author/alan_gauld
Follow my photo-blog on Flickr at:
http://www.flickr.com/photos/alangauldphotos



From breamoreboy at gmail.com  Fri Nov 26 12:36:53 2021
From: breamoreboy at gmail.com (Mark Lawrence)
Date: Fri, 26 Nov 2021 17:36:53 +0000
Subject: [Tutor] Using super() in classes
In-Reply-To: <snr3cm$c46$1@ciao.gmane.io>
References: <CAO1OCwY3xnG72QTW-vpsRsFGwE-BT7M_HTdajrftDposSeicQA@mail.gmail.com>
 <snr3cm$c46$1@ciao.gmane.io>
Message-ID: <2da9398c-9cc2-1b4c-8d8e-6d60265b094d@gmail.com>

On 26/11/2021 16:52, Alan Gauld via Tutor wrote:

snipped to pieces as I just want to point people to 
https://rhettinger.wordpress.com/2011/05/26/super-considered-super/ and 
https://www.youtube.com/watch?v=EiOglTERPEo

-- 
My fellow Pythonistas, ask not what our language can do for you, ask
what you can do for our language.

Mark Lawrence


From manpritsinghece at gmail.com  Fri Nov 26 20:30:37 2021
From: manpritsinghece at gmail.com (Manprit Singh)
Date: Sat, 27 Nov 2021 07:00:37 +0530
Subject: [Tutor] Clarity about MRO (method resolution order )
Message-ID: <CAO1OCwZJY46Z06bsAVyWsQagGW7_a=--XAnZv2U6VcghRcWJWA@mail.gmail.com>

Dear sir,
Consider the code given below :

class ABC:
    def show(self):
        print("HELLO")

class ABCD(ABC):
    def show(self):
        print("hello")

class ABCDE(ABC):
    def show(self):
        print("Hello")

class ABC12(ABCD, ABCDE):
    pass

obj = ABC12()
obj.show()   # gives the output hello

Just need to make myself clear about the output i got after executing this
code
The classes ABC, ABCD, ABCDE all have a method with the same name show().
obj is the instance of class ABC12. executing obj.show() will execute the
show ()
of ABCD class, the answer lies with the MRO of ABC12 class

ABC12.mro()  will result in

[__main__.ABC12, __main__.ABCD, __main__.ABCDE, __main__.ABC, object]

According to this MRO, show() will be searched in the classes in the order

given in the output of ABC12.mro(). show() was first searched in ABC12 class,

it was not there , and hence it was searched in ABCD class, it was present

and hence executed.

Am I right with this explanation ?

From manpritsinghece at gmail.com  Fri Nov 26 20:51:48 2021
From: manpritsinghece at gmail.com (Manprit Singh)
Date: Sat, 27 Nov 2021 07:21:48 +0530
Subject: [Tutor] Multiple inheritance - Need clarity
Message-ID: <CAO1OCwbCUkp+DKEb4PFwUM_2ioVQOiYe=5pw90p66kTJLk557Q@mail.gmail.com>

Dear sir,

Below given is a toy example , that calculates the surface area of a
cylinder (area of circles on both sides + area of cylinder wall)

import math
class Circle:

    def __init__(self, radius):
        self.radius = radius

    def circle_area(self):
        return math.pi * self.radius**2

class Rectangle:

    def __init__(self, s1, s2):
        self.side1 = s1
        self.side2 = s2

    def rectangle_area(self):
        return self.side1 * self.side2

class Cylinder(Circle, Rectangle):

    def __init__(self, rad, ht):
        Circle.__init__(self, rad)
        Rectangle.__init__(self, 2*math.pi*rad, ht)

    def cylinder_surface_area(self):
        return 2 * self.circle_area() + self.rectangle_area()

cyl = Cylinder(3, 10)
cyl.cylinder_surface_area()

Gives the answer =

245.04422698000386

Just need to know that the way i have called __init__ of circle & rectangle

inside the init of Cylinder ok or not ? the way i have used circle_area &

rectangle_area inside cylinder_surface_area  is correct or not ?

Kindly guide to do this problem in a better way

Regards

Manprit Singh

From wlfraed at ix.netcom.com  Fri Nov 26 22:14:18 2021
From: wlfraed at ix.netcom.com (Dennis Lee Bieber)
Date: Fri, 26 Nov 2021 22:14:18 -0500
Subject: [Tutor] Multiple inheritance - Need clarity
References: <CAO1OCwbCUkp+DKEb4PFwUM_2ioVQOiYe=5pw90p66kTJLk557Q@mail.gmail.com>
Message-ID: <p473qg9t7a2i471euvk5kt5676166mc4ef@4ax.com>

On Sat, 27 Nov 2021 07:21:48 +0530, Manprit Singh
<manpritsinghece at gmail.com> declaimed the following:

>Dear sir,
>
>Below given is a toy example , that calculates the surface area of a
>cylinder (area of circles on both sides + area of cylinder wall)
>
>import math
>class Circle:
>
>    def __init__(self, radius):
>        self.radius = radius
>
>    def circle_area(self):
>        return math.pi * self.radius**2
>
>class Rectangle:
>
>    def __init__(self, s1, s2):
>        self.side1 = s1
>        self.side2 = s2
>
>    def rectangle_area(self):
>        return self.side1 * self.side2
>
>class Cylinder(Circle, Rectangle):
>
>    def __init__(self, rad, ht):
>        Circle.__init__(self, rad)
>        Rectangle.__init__(self, 2*math.pi*rad, ht)
>
>    def cylinder_surface_area(self):
>        return 2 * self.circle_area() + self.rectangle_area()
>
>cyl = Cylinder(3, 10)
>cyl.cylinder_surface_area()
>
>Gives the answer =
>
>245.04422698000386
>
>Just need to know that the way i have called __init__ of circle & rectangle
>inside the init of Cylinder ok or not ? the way i have used circle_area &
>rectangle_area inside cylinder_surface_area  is correct or not ?
>
>Kindly guide to do this problem in a better way

	And again you are asking for stylistic approval, not if the code is
"correct" or "incorrect".

	Personally, I would not use inheritance for this example but
composition.

	cyl.cylinder_surface_area() is somewhat redundant. You just want the
surface area of /whatever/ object is of interest. Consider the situation
of...

objs = [ cylinder, cube, dodecahedron ]
for obj in objs:
	sa = obj.surface_area()

	You would want a common name for surface area of 3D objects -- not a
name specific to each object.

	But that also means your 2D components (circle and rectangle) should
similarily have just an 
	
	obj.area()

method to be called.

	But with your multiple inheritance, you would have to explicitly call 
		
	top_bottom_area = 2 * Circle.area()
	column_area = Rectangle.area()

as using super... will only call the first item in the MRO.

	Using composition it would be something like...

class Cylinder():
	def __init__(self, height, radius):
		top_bottom = Circle(radius)
		column = Rectangle(height, radius)
	def area(self):
		return self.top_bottom.area() * 2 + self.column.area()

class Sphere():
	#I'm not going to derive the area of dodecahedron <G>
	def __init__(self, radius):
		self.radius = radius
	def area(self):
		return 4 * math.pi * self.radius ** 2

	There is no inheritance, and no overridden methods, in this structure.
There is only the .area() method for all classes which allows a list of all
object types to be processed with the same logic.	Obviously, for 2D
Circle() and Rectangle() objects, .area() returns the planar area, while
for 3D Cylinder() and Sphere() it returns surface area.

	objs = [	Cylinder(10, 3),
			Circle(4),
			Rectangle(3, 4),
			Sphere(5)	]

	for obj in objs:
		print(	obj.area()	)



-- 
	Wulfraed                 Dennis Lee Bieber         AF6VN
	wlfraed at ix.netcom.com    http://wlfraed.microdiversity.freeddns.org/


From wlfraed at ix.netcom.com  Fri Nov 26 22:46:56 2021
From: wlfraed at ix.netcom.com (Dennis Lee Bieber)
Date: Fri, 26 Nov 2021 22:46:56 -0500
Subject: [Tutor] Multiple inheritance - Need clarity
References: <CAO1OCwbCUkp+DKEb4PFwUM_2ioVQOiYe=5pw90p66kTJLk557Q@mail.gmail.com>
 <p473qg9t7a2i471euvk5kt5676166mc4ef@4ax.com>
Message-ID: <8393qg9qqr2m4sjaahht5lsia10djr38ii@4ax.com>

	o/~ Talking to myself in public o/~

On Fri, 26 Nov 2021 22:14:18 -0500, Dennis Lee Bieber
<wlfraed at ix.netcom.com> declaimed the following:

>	Personally, I would not use inheritance for this example but
>composition.
>

	To better clarify...

	Inheritance is used if/when the subclass IS also a parent class

	A Cylinder is NOT a Circle, NOR is it a Rectangle.

Class Carnivore():
	...

Class Mammal():
	...

Class Fish():
	...

Class Cat(Mammal, Carnivore):
	...

Class Shark(Fish, Carnivore):
	...

	A Cat IS A Mammal.
	A Cat IS also A Carnivore.

	A Shark IS A Fish.
	A Shark IS also A Carnivore.

	Composition is used when the class is made up of other objects.

	A Cylinder HAS A Circle (actually, two identical for top and bottom), A
Cylinder also HAS A Rectangle (using your style for the column)

Class Vehicle():
	...

Class Wheel():
	...

Class Engine():
	...

Class InternalCombustion(Engine):
	#internal combustion IS A engine

Class Diesel(Engine):
	#similarly

Class PassengerCar():
	def __init__(self, engine):
		self.wheels = { "LF" : Wheel(...),
					"RF": Wheel(...),
					"LR" : Wheel(...),
					"RR" : Wheel(...)	]
		self.engine = engine

	A PassengerCar HAS multiple Wheels, a PassengerCar HAS an engine.
(some sports cars may have larger rear tires than front tires -- I've only
hinted that this could be the case her -- would have to add parameters to
__init__ to allow for such.


	Personally, I wouldn't even use composition for your Cylinder() -- I'd
just save radius and height directly, rather than the indirect radius (in
Circle()) and height/width (in Rectangle) -- do you expect anyone to ask
for
	cylinder.rectangle.width
?
I'd think anyone working with a cylinder would be more likely to ask for
	cylinder.radius
	cylinder.height
NOT
	cylinder.circle.radius
	cylinder.rectangle.height
(who thinks of /rectangles/ when discussing a cylinder?) Even worse, your
rectangle just has side1 and side2 -- how does a user know which is the
height, and which is the width?


-- 
	Wulfraed                 Dennis Lee Bieber         AF6VN
	wlfraed at ix.netcom.com    http://wlfraed.microdiversity.freeddns.org/


From alan.gauld at yahoo.co.uk  Sat Nov 27 05:46:39 2021
From: alan.gauld at yahoo.co.uk (Alan Gauld)
Date: Sat, 27 Nov 2021 10:46:39 +0000
Subject: [Tutor] Clarity about MRO (method resolution order )
In-Reply-To: <CAO1OCwZJY46Z06bsAVyWsQagGW7_a=--XAnZv2U6VcghRcWJWA@mail.gmail.com>
References: <CAO1OCwZJY46Z06bsAVyWsQagGW7_a=--XAnZv2U6VcghRcWJWA@mail.gmail.com>
Message-ID: <snt2af$4ab$1@ciao.gmane.io>

On 27/11/2021 01:30, Manprit Singh wrote:

> ABC12.mro()  will result in
> 
> [__main__.ABC12, __main__.ABCD, __main__.ABCDE, __main__.ABC, object]
> 
> According to this MRO, show() will be searched in the classes in the order
> given in the output of ABC12.mro(). show() was first searched in ABC12 class,
> it was not there , and hence it was searched in ABCD class, it was present
> and hence executed.
> 
> Am I right with this explanation ?

Yes, absolutely.


-- 
Alan G
Author of the Learn to Program web site
http://www.alan-g.me.uk/
http://www.amazon.com/author/alan_gauld
Follow my photo-blog on Flickr at:
http://www.flickr.com/photos/alangauldphotos



From alan.gauld at yahoo.co.uk  Sat Nov 27 06:03:20 2021
From: alan.gauld at yahoo.co.uk (Alan Gauld)
Date: Sat, 27 Nov 2021 11:03:20 +0000
Subject: [Tutor] Multiple inheritance - Need clarity
In-Reply-To: <CAO1OCwbCUkp+DKEb4PFwUM_2ioVQOiYe=5pw90p66kTJLk557Q@mail.gmail.com>
References: <CAO1OCwbCUkp+DKEb4PFwUM_2ioVQOiYe=5pw90p66kTJLk557Q@mail.gmail.com>
Message-ID: <snt39p$16n3$1@ciao.gmane.io>

On 27/11/2021 01:51, Manprit Singh wrote:
> Below given is a toy example , that calculates the surface area of a
> cylinder (area of circles on both sides + area of cylinder wall)

One of the problems with OOP is that trying to understand it using
toy examples tends to result in bad OO code and hence unclear
understanding. Themore realistic an example you can come up
with the more likely you are to understand how the code works
and why.

> import math
> class Circle:
>     def __init__(self, radius):
>         self.radius = radius
>     def circle_area(self):
>         return math.pi * self.radius**2
> 
> class Rectangle:
>     def __init__(self, s1, s2):
>         self.side1 = s1
>         self.side2 = s2
>     def rectangle_area(self):
>         return self.side1 * self.side2
> 
> class Cylinder(Circle, Rectangle):

And here is the problem.
Inheritance implies an IS-A relationship.
This code says that Cylinder IS A Circle and at the same
time IS also a Rectangle. ie. That you could insert a
Cylinder instance anywhere that a Circle or Rectangle
was expected.

However a cylinder is not a Circle or a Rectangle,
rather it is *composed* of 2 circles and (arguably)
a rectangle. One of the big problems with inheritance
in general, and especially with Multiple inheritance,
is that it gets abused as a method to reuse code
rather than as a model of the problem domain.
Very often people use inheritance when they should use
composition/delegation.

>     def __init__(self, rad, ht):
>         Circle.__init__(self, rad)
>         Rectangle.__init__(self, 2*math.pi*rad, ht)

But this is where you should use super()
Otherwise you will call the object.init twice. (In
this case, not a problem but it could be in real code.
For example, say the root object maintains a counter
of instances, calling it twice would lead to double
counting). Also, you will make your Cylinder
non-compatible with super() in any derived
Cylinders(such as ColouredCylinder say...)

> Just need to know that the way i have called __init__ of circle & rectangle
> inside the init of Cylinder ok or not ? the way i have used circle_area &
> rectangle_area inside cylinder_surface_area  is correct or not ?

Syntactically correct but stylistically and idiomatically wrong.

And wrong primarily because you are trying to use inheritance
where you should be using composition.

A valid superclass for all of these objects might be Shape which
in turn might be sub-classed into 2DShape and 3DShape. Circle
and rectangle would be sub-classes of 2DShape while Cylinder
would be a subclass of 3DShape.

But I would be the first to agree that OOP is difficult to
grasp without using it on larger projects. Its value is not
always evident in small scale code. But you need small scale
to learn the techniques. So often you have to just work with
it and trust that it will make sense later...

-- 
Alan G
Author of the Learn to Program web site
http://www.alan-g.me.uk/
http://www.amazon.com/author/alan_gauld
Follow my photo-blog on Flickr at:
http://www.flickr.com/photos/alangauldphotos



From alan.gauld at yahoo.co.uk  Sat Nov 27 06:06:10 2021
From: alan.gauld at yahoo.co.uk (Alan Gauld)
Date: Sat, 27 Nov 2021 11:06:10 +0000
Subject: [Tutor] Multiple inheritance - Need clarity
In-Reply-To: <p473qg9t7a2i471euvk5kt5676166mc4ef@4ax.com>
References: <CAO1OCwbCUkp+DKEb4PFwUM_2ioVQOiYe=5pw90p66kTJLk557Q@mail.gmail.com>
 <p473qg9t7a2i471euvk5kt5676166mc4ef@4ax.com>
Message-ID: <snt3f2$16n3$2@ciao.gmane.io>

On 27/11/2021 03:14, Dennis Lee Bieber wrote:

> 	But with your multiple inheritance, you would have to explicitly call 
> 		
> 	top_bottom_area = 2 * Circle.area()
> 	column_area = Rectangle.area()
> 
> as using super... will only call the first item in the MRO.

Ah, good point. My recommendation to use super() here was
misplaced. You need to call both.

-- 
Alan G
Author of the Learn to Program web site
http://www.alan-g.me.uk/
http://www.amazon.com/author/alan_gauld
Follow my photo-blog on Flickr at:
http://www.flickr.com/photos/alangauldphotos



From tariqkhasiri at gmail.com  Fri Nov 26 21:20:28 2021
From: tariqkhasiri at gmail.com (Tariq Khasiri)
Date: Sat, 27 Nov 2021 08:20:28 +0600
Subject: [Tutor] Explanation of one - hot encoding
Message-ID: <CAFy_oHBJz9fSjf9SkekLOAw368xHXjiTgzDj+dO7MyNU=bajiA@mail.gmail.com>

This following line is from a kernel I am trying to replicate from Spotify
songs data. Could anyone kindly explain what this line means ?

? In terms of encoding our artists and our genres we see one-hot encoding
is a bad idea here considering the cardinality of those features therefore
we will dummy encode the genres and replace the artist names with numerical
values closer to the model selection stage. ?

From alan.gauld at yahoo.co.uk  Sat Nov 27 07:27:41 2021
From: alan.gauld at yahoo.co.uk (Alan Gauld)
Date: Sat, 27 Nov 2021 12:27:41 +0000
Subject: [Tutor] Explanation of one - hot encoding
In-Reply-To: <CAFy_oHBJz9fSjf9SkekLOAw368xHXjiTgzDj+dO7MyNU=bajiA@mail.gmail.com>
References: <CAFy_oHBJz9fSjf9SkekLOAw368xHXjiTgzDj+dO7MyNU=bajiA@mail.gmail.com>
Message-ID: <snt87t$fd8$1@ciao.gmane.io>

On 27/11/2021 02:20, Tariq Khasiri wrote:
> This following line is from a kernel I am trying to replicate from Spotify
> songs data. Could anyone kindly explain what this line means ?
> 
> ? In terms of encoding our artists and our genres we see one-hot encoding
> is a bad idea here considering the cardinality of those features therefore
> we will dummy encode the genres and replace the artist names with numerical
> values closer to the model selection stage. ?

This has nothing to do with Python and should really be
addressed to the Spotify community I suspect. I certainly
have no clue what most of it means.

My guess is that one-hot is a typo for one-shot but that
is purely a guess!

-- 
Alan G
Author of the Learn to Program web site
http://www.alan-g.me.uk/
http://www.amazon.com/author/alan_gauld
Follow my photo-blog on Flickr at:
http://www.flickr.com/photos/alangauldphotos



From lggeorgieva at gmail.com  Sat Nov 27 07:30:17 2021
From: lggeorgieva at gmail.com (Lilia Georgieva)
Date: Sat, 27 Nov 2021 12:30:17 +0000
Subject: [Tutor] Explanation of one - hot encoding
In-Reply-To: <snt87t$fd8$1@ciao.gmane.io>
References: <CAFy_oHBJz9fSjf9SkekLOAw368xHXjiTgzDj+dO7MyNU=bajiA@mail.gmail.com>
 <snt87t$fd8$1@ciao.gmane.io>
Message-ID: <CAFjd6rCFhjOfeNfv_W51xXzAYhSKHSaaHwyv4eSEmuAdeTrCCg@mail.gmail.com>

Hi,

Here is a Wikipedia article on one hot encoding. This is fairly common.

https://en.m.wikipedia.org/wiki/One-hot

Lilia

On Sat, Nov 27, 2021, 12:28 Alan Gauld via Tutor <tutor at python.org> wrote:

> On 27/11/2021 02:20, Tariq Khasiri wrote:
> > This following line is from a kernel I am trying to replicate from
> Spotify
> > songs data. Could anyone kindly explain what this line means ?
> >
> > ? In terms of encoding our artists and our genres we see one-hot encoding
> > is a bad idea here considering the cardinality of those features
> therefore
> > we will dummy encode the genres and replace the artist names with
> numerical
> > values closer to the model selection stage. ?
>
> This has nothing to do with Python and should really be
> addressed to the Spotify community I suspect. I certainly
> have no clue what most of it means.
>
> My guess is that one-hot is a typo for one-shot but that
> is purely a guess!
>
> --
> Alan G
> Author of the Learn to Program web site
> http://www.alan-g.me.uk/
> http://www.amazon.com/author/alan_gauld
> Follow my photo-blog on Flickr at:
> http://www.flickr.com/photos/alangauldphotos
>
>
> _______________________________________________
> Tutor maillist  -  Tutor at python.org
> To unsubscribe or change subscription options:
> https://mail.python.org/mailman/listinfo/tutor
>

From manpritsinghece at gmail.com  Sat Nov 27 10:36:14 2021
From: manpritsinghece at gmail.com (Manprit Singh)
Date: Sat, 27 Nov 2021 21:06:14 +0530
Subject: [Tutor] Multiple inheritance - Need clarity
In-Reply-To: <snt3f2$16n3$2@ciao.gmane.io>
References: <CAO1OCwbCUkp+DKEb4PFwUM_2ioVQOiYe=5pw90p66kTJLk557Q@mail.gmail.com>
 <p473qg9t7a2i471euvk5kt5676166mc4ef@4ax.com> <snt3f2$16n3$2@ciao.gmane.io>
Message-ID: <CAO1OCwaLDxQVd5r74U5OQbewFUH4QFrMj2aruAD_JxCK7T0fmQ@mail.gmail.com>

Once again many many thanks  to Dennis and Alan sir for this mail .
Actually I do work with Scientific computing  (Numpy and pandas &
matplotlib and Scikit-learn the most ), my work is rarely related to OOPS
(Just making some simple classes for transformations etc.) . Just trying to
learn....

Regards
Manprit Singh


On Sat, Nov 27, 2021 at 4:40 PM Alan Gauld via Tutor <tutor at python.org>
wrote:

> On 27/11/2021 03:14, Dennis Lee Bieber wrote:
>
> >       But with your multiple inheritance, you would have to explicitly
> call
> >
> >       top_bottom_area = 2 * Circle.area()
> >       column_area = Rectangle.area()
> >
> > as using super... will only call the first item in the MRO.
>
> Ah, good point. My recommendation to use super() here was
> misplaced. You need to call both.
>
> --
> Alan G
> Author of the Learn to Program web site
> http://www.alan-g.me.uk/
> http://www.amazon.com/author/alan_gauld
> Follow my photo-blog on Flickr at:
> http://www.flickr.com/photos/alangauldphotos
>
>
> _______________________________________________
> Tutor maillist  -  Tutor at python.org
> To unsubscribe or change subscription options:
> https://mail.python.org/mailman/listinfo/tutor
>

From manpritsinghece at gmail.com  Sat Nov 27 10:45:24 2021
From: manpritsinghece at gmail.com (Manprit Singh)
Date: Sat, 27 Nov 2021 21:15:24 +0530
Subject: [Tutor] Explanation of one - hot encoding
In-Reply-To: <CAFy_oHBJz9fSjf9SkekLOAw368xHXjiTgzDj+dO7MyNU=bajiA@mail.gmail.com>
References: <CAFy_oHBJz9fSjf9SkekLOAw368xHXjiTgzDj+dO7MyNU=bajiA@mail.gmail.com>
Message-ID: <CAO1OCwbC1ijw2uBOBzrWJqc-yZVL46FgNNzMWD+RxV1Bwmf1YA@mail.gmail.com>

Dear sir,

One hot encoding is basically a preprocessing step in machine learning ,
where a categorical feature is encoded as a numeric array of 0 and 1 . One
hot encoding is not considered good when a feature has a large number of
unique values in it .

Regards


On Sat, Nov 27, 2021 at 5:08 PM Tariq Khasiri <tariqkhasiri at gmail.com>
wrote:

> This following line is from a kernel I am trying to replicate from Spotify
> songs data. Could anyone kindly explain what this line means ?
>
> ? In terms of encoding our artists and our genres we see one-hot encoding
> is a bad idea here considering the cardinality of those features therefore
> we will dummy encode the genres and replace the artist names with numerical
> values closer to the model selection stage. ?
> _______________________________________________
> Tutor maillist  -  Tutor at python.org
> To unsubscribe or change subscription options:
> https://mail.python.org/mailman/listinfo/tutor
>

From wlfraed at ix.netcom.com  Sat Nov 27 11:48:01 2021
From: wlfraed at ix.netcom.com (Dennis Lee Bieber)
Date: Sat, 27 Nov 2021 11:48:01 -0500
Subject: [Tutor] Multiple inheritance - Need clarity
References: <CAO1OCwbCUkp+DKEb4PFwUM_2ioVQOiYe=5pw90p66kTJLk557Q@mail.gmail.com>
 <p473qg9t7a2i471euvk5kt5676166mc4ef@4ax.com> <snt3f2$16n3$2@ciao.gmane.io>
 <CAO1OCwaLDxQVd5r74U5OQbewFUH4QFrMj2aruAD_JxCK7T0fmQ@mail.gmail.com>
Message-ID: <ltn4qgp9re604f4s5k6538pj5k5h1ocgmp@4ax.com>

On Sat, 27 Nov 2021 21:06:14 +0530, Manprit Singh
<manpritsinghece at gmail.com> declaimed the following:

>Once again many many thanks  to Dennis and Alan sir for this mail .
>Actually I do work with Scientific computing  (Numpy and pandas &
>matplotlib and Scikit-learn the most ), my work is rarely related to OOPS
>(Just making some simple classes for transformations etc.) . Just trying to
>learn....
>

	Numpy, matplotlib, et al. are loaded with OOP -- just spend some time
studying the source files (at least those in Python; for speed most of
those libraries will eventually devolve into calls to C/C++ libraries)

	Also to be aware of: OOAD (object oriented analysis and design) and OOP
(object oriented programming) are related, but separate (one can coerce
object designs into non-OOP languages by using a coding style where the
object [a record structure] is manually passed to methods, though managing
inheritance is difficult -- after all, original C++ was a massive set of
macros that translated the C++ syntax of the time into regular K&R C).


-- 
	Wulfraed                 Dennis Lee Bieber         AF6VN
	wlfraed at ix.netcom.com    http://wlfraed.microdiversity.freeddns.org/


From tariqkhasiri at gmail.com  Sat Nov 27 11:41:30 2021
From: tariqkhasiri at gmail.com (Tariq Khasiri)
Date: Sat, 27 Nov 2021 22:41:30 +0600
Subject: [Tutor] Explanation of one - hot encoding
In-Reply-To: <snt87t$fd8$1@ciao.gmane.io>
References: <CAFy_oHBJz9fSjf9SkekLOAw368xHXjiTgzDj+dO7MyNU=bajiA@mail.gmail.com>
 <snt87t$fd8$1@ciao.gmane.io>
Message-ID: <CAFy_oHASjGLU-1b_iXTQnYPP5KNTibJC4usX2x+pZ+5hY0PTqw@mail.gmail.com>

so grateful to everyone who has been kind enough to give their valuable
feedback. now i have a better grip over the whole thing - thanks to all of
you !

On Sat, Nov 27, 2021 at 6:29 PM Alan Gauld via Tutor <tutor at python.org>
wrote:

> On 27/11/2021 02:20, Tariq Khasiri wrote:
> > This following line is from a kernel I am trying to replicate from
> Spotify
> > songs data. Could anyone kindly explain what this line means ?
> >
> > ? In terms of encoding our artists and our genres we see one-hot encoding
> > is a bad idea here considering the cardinality of those features
> therefore
> > we will dummy encode the genres and replace the artist names with
> numerical
> > values closer to the model selection stage. ?
>
> This has nothing to do with Python and should really be
> addressed to the Spotify community I suspect. I certainly
> have no clue what most of it means.
>
> My guess is that one-hot is a typo for one-shot but that
> is purely a guess!
>
> --
> Alan G
> Author of the Learn to Program web site
> http://www.alan-g.me.uk/
> http://www.amazon.com/author/alan_gauld
> Follow my photo-blog on Flickr at:
> http://www.flickr.com/photos/alangauldphotos
>
>
> _______________________________________________
> Tutor maillist  -  Tutor at python.org
> To unsubscribe or change subscription options:
> https://mail.python.org/mailman/listinfo/tutor
>

From alan.gauld at yahoo.co.uk  Sat Nov 27 12:48:36 2021
From: alan.gauld at yahoo.co.uk (Alan Gauld)
Date: Sat, 27 Nov 2021 17:48:36 +0000
Subject: [Tutor] Multiple inheritance - Need clarity
In-Reply-To: <ltn4qgp9re604f4s5k6538pj5k5h1ocgmp@4ax.com>
References: <CAO1OCwbCUkp+DKEb4PFwUM_2ioVQOiYe=5pw90p66kTJLk557Q@mail.gmail.com>
 <p473qg9t7a2i471euvk5kt5676166mc4ef@4ax.com> <snt3f2$16n3$2@ciao.gmane.io>
 <CAO1OCwaLDxQVd5r74U5OQbewFUH4QFrMj2aruAD_JxCK7T0fmQ@mail.gmail.com>
 <ltn4qgp9re604f4s5k6538pj5k5h1ocgmp@4ax.com>
Message-ID: <sntr1k$sa2$1@ciao.gmane.io>

On 27/11/2021 16:48, Dennis Lee Bieber wrote:

> inheritance is difficult -- after all, original C++ was a massive set of
> macros that translated the C++ syntax of the time into regular K&R C).

Indeed, and ultimately all languages devolve to machine code and
none of those are even remotely object oriented!

-- 
Alan G
Author of the Learn to Program web site
http://www.alan-g.me.uk/
http://www.amazon.com/author/alan_gauld
Follow my photo-blog on Flickr at:
http://www.flickr.com/photos/alangauldphotos



From phillor9 at gmail.com  Sat Nov 27 22:51:02 2021
From: phillor9 at gmail.com (Phil)
Date: Sun, 28 Nov 2021 14:51:02 +1100
Subject: [Tutor] pylint(too-many-nested-blocks)
Message-ID: <2c34791d-dc21-4070-82d2-1c98d67616ce@gmail.com>

"https://pycodequ.al/docs/pylint-messages/r1702-too-many-nested-blocks.html" 
describes this error as:

"Used when a function or method has too many nested blocks. This makes 
the code less understandable and maintainable."

The following is one of several functions that fits this description and 
I'm wondering how I might reduce the number of for-loops. If the number 
of for-loops cannot be reduced then I suppose the function should be 
broken up into smaller functions. The problem is, as I see it, little of 
the code is reusable in other functions that also have too many nested 
blocks.

 ??? def pointingPairRow(self):
 ??????? """
 ??????? If a candidate is present in only two cells of a box, then it 
must be the
 ??????? solution for one of these two cells. If these two cells belong 
to the same row,
 ??????? then this candidate can not be the solution in any other cell 
of the same row.
 ??????? """
 ??????? box_start = [(0, 0), (0, 3), (0, 6),
 ??????????????????? (3, 0), (3, 3), (3, 6),
 ??????????????????? (6, 0), (6, 3), (6, 6)
 ??????????????????? ]

 ??????? for x, y in box_start:
 ??????????? pairs = Counter()

 ??????????? for number in range(1, 10):
 ??????????????? number= str(number)

 ??????????????? for row in range(x, x + 3):
 ??????????????????? for col in range(y, y + 3):
 ??????????????????????? if len(self.solution[row][col]) > 1 and number 
in self.solution[row][col]:
 ??????????????????????????? pairs[number] += 1

 ??????????? for item, count in pairs.items():
 ??????????????? if count == 2:? # candidate
 ??????????????????? for row in range(x, x + 3):
 ??????????????????????? icount = 0
 ??????????????????????? col_list = []

 ??????????????????????? for col in range(y, y + 3):
 ??????????????????????????? if item in self.solution[row][col]:
 ??????????????????????????????? icount += 1
 ??????????????????????????????? col_list.append(col)

 ??????????????????????????? if icount == 2:
 ??????????????????????????????? for c in range(self.num_cols):
 ??????????????????????????????????? if? len(self.solution[row][c]) > 1 
and item in self.solution[row][c] and c not in col_list:
 ??????????????????????????????????????? self.solution[row][c] -= set(item)

Also, the 3 for-loops before "if count == 2" don't need to be repeated 
once the candidate has been removed from the row with 
"self.solution[row][c] -= set(item)". Setting a boolean switch here to 
prevent the for-loops from continuing does the job but it adds yet 
another "if" statement.

The function works and so it's logically correct but it's messy and 
inefficient.

-- 
Regards,
Phil


From PyTutor at DancesWithMice.info  Sun Nov 28 03:45:50 2021
From: PyTutor at DancesWithMice.info (dn)
Date: Sun, 28 Nov 2021 21:45:50 +1300
Subject: [Tutor] pylint(too-many-nested-blocks)
In-Reply-To: <2c34791d-dc21-4070-82d2-1c98d67616ce@gmail.com>
References: <2c34791d-dc21-4070-82d2-1c98d67616ce@gmail.com>
Message-ID: <703ee90c-2d81-5ea3-91aa-7b2a399e4531@DancesWithMice.info>

On 28/11/2021 16.51, Phil wrote:
> "https://pycodequ.al/docs/pylint-messages/r1702-too-many-nested-blocks.html"
> describes this error as:
> 
> "Used when a function or method has too many nested blocks. This makes
> the code less understandable and maintainable."
> 
> The following is one of several functions that fits this description and
> I'm wondering how I might reduce the number of for-loops. If the number
> of for-loops cannot be reduced then I suppose the function should be
> broken up into smaller functions. The problem is, as I see it, little of
> the code is reusable in other functions that also have too many nested
> blocks.
> 
> ??? def pointingPairRow(self):
> ??????? """
> ??????? If a candidate is present in only two cells of a box, then it
> must be the
> ??????? solution for one of these two cells. If these two cells belong
> to the same row,
> ??????? then this candidate can not be the solution in any other cell of
> the same row.
> ??????? """
> ??????? box_start = [(0, 0), (0, 3), (0, 6),
> ??????????????????? (3, 0), (3, 3), (3, 6),
> ??????????????????? (6, 0), (6, 3), (6, 6)
> ??????????????????? ]
> 
> ??????? for x, y in box_start:
> ??????????? pairs = Counter()
> 
> ??????????? for number in range(1, 10):
> ??????????????? number= str(number)
> 
> ??????????????? for row in range(x, x + 3):
> ??????????????????? for col in range(y, y + 3):
> ??????????????????????? if len(self.solution[row][col]) > 1 and number
> in self.solution[row][col]:
> ??????????????????????????? pairs[number] += 1
> 
> ??????????? for item, count in pairs.items():
> ??????????????? if count == 2:? # candidate
> ??????????????????? for row in range(x, x + 3):
> ??????????????????????? icount = 0
> ??????????????????????? col_list = []
> 
> ??????????????????????? for col in range(y, y + 3):
> ??????????????????????????? if item in self.solution[row][col]:
> ??????????????????????????????? icount += 1
> ??????????????????????????????? col_list.append(col)
> 
> ??????????????????????????? if icount == 2:
> ??????????????????????????????? for c in range(self.num_cols):
> ??????????????????????????????????? if? len(self.solution[row][c]) > 1
> and item in self.solution[row][c] and c not in col_list:
> ??????????????????????????????????????? self.solution[row][c] -= set(item)
> 
> Also, the 3 for-loops before "if count == 2" don't need to be repeated
> once the candidate has been removed from the row with
> "self.solution[row][c] -= set(item)". Setting a boolean switch here to
> prevent the for-loops from continuing does the job but it adds yet
> another "if" statement.
> 
> The function works and so it's logically correct but it's messy and
> inefficient.


Does Python itself see this as an error and stop working, or is it only
the code-checker s/w?

If Python, then I've never reached that point, which makes you better
than me - or does it?


Were we conducting a Code Review, this function would definitely attract
criticism. You have already recognised the complexity, but seem somewhat
satisfied - on the  grounds that the whole works. (which may be as good
a measure as any other - depending upon application!)

The two (easily agreed) criticisms are "messy" and "inefficient".

Here are two more ideas: "cyclomatic complexity" and "readability".

Some say that code should be written with the view that it is more
important that it can be read by humans than by computers. This seems
contra-indicated when the process of programming is to 'instruct the
computer'. However, consider the life-time of a program[me]. Also, that
computers 'read' code with a very narrow and dogmatic point-of-view,
compared with us-peoples.

We also talk about your future-self, meaning you in (a notional)
six-months' time. In other words, someone who is reading this for the
first time ever, or you, after sufficient time has passed that a lot of
your 'thinking' that went into the construction of this code has
disappeared from even the back of your mind.

Question: is it/will it be easy to read?

Here's where things become rather subjective. You (no criticism) seem to
have a mathematical view of programming, as revealed by your choice of
example-problems and love of abbreviated identifiers. That said, a
docstring describes the function - so gold-star for that - even if
"candidate" and "solution" are beyond my ken.

Perhaps the point to invite some thought into comparing the 'how' and
the 'why' of a piece of code - two important questions in the mind of a
reader/reviewer!

I have been criticised (but exhibit little remorse) for breaking things
down into "smaller" units of code than others feel necessary. Maybe
you'd agree with that. Like I said "subjective"! Hasn't "stepwise
decomposition" been mentioned before?


Now is a good time pick-up the testing tool's feedback: "understandable
and maintainable". It's not merely a matter of
"readability"/"understandability", but also maintainability - and that
of the objectives of the tool: "testability".

How can you prove to me that this code actually does do 'what it says on
the tin [/can]'? Let's say that there is a suite of testing code, and
one of those indicates that there is an error somewhere 'around' the
innermost/most deeply nested (and last) for-loop. How can you (or I, or
A.N.Other) proceed to correct ("maintain") this code? How much larger
will the problem seem, if it is not revealed by the test-suite, but is
'discovered' by some (not-so) innocent user in the proverbial
six-month's time?

How easy will it be to see if this notional problem (I'm not saying
there is one!) if 'inside' that for-loop, or is somewhere in the code
which manipulates the data which is subsequently 'fed' into the loop?

Another consideration: if the preceding steps (prior to that inner
for-loop) are 'expensive', particularly in terms of time, how many
test-cycles, checks, and detection-runs can you afford? If it were
'cheaper'/faster to test, how many now?


I like the old saw: that if "debugging" is taking the bugs out of code,
then programming must be the process of putting them in! Accordingly,
there is a lesson many find hard to learn/admit to themselves - it is
better to program[me] 'defensively' (in the expectation of errors), that
to code arrogantly (overly-impressed with one's own abilities,
assumptions of perfection, feelings of invincibility,  ...).
- or maybe that's an admission that I'm just not very good at it?

If the for-loop is detached from the rest of the code, can you give it a
name? If-then, you can also test it in isolation from the rest of the
functionality. This morning I needed to add the ability to remove a
single item (pop) from a multi-dimensional data-structure, and further
functionality to remove an entire 'row' (sound familiar?). I could have
'tested' these 'within' the application which uses the data-structure.
Why not? That's where the code is actually being used - and if it works
there, it must 'work'! Right? When the two test harnesses were
constructed and the code seemed to be working, one of them failed at the
last test-step. It had 'passed' before! It failed because of a 'fix',
installed to cover another previously-failing test-step. Oops!
(yes, big surprise, I make programming errors - but don't bother to
circle this date in the calendar, you'll quickly run out of ink, and
obliterate your calendar should you monitor me that closely!)

The reason why the small(er) code-units were worth what may have seemed
like 'more effort than necessary', was because it was so much quicker
and easier to test the code as I wrote it*, it was easy to find/be shown
errors as they were made, and it was easy to see that a 'fix' in one
place, caused an issue under another set of circumstances. All while the
actual code was fresh in my mind, and not when I would be more
interested in the application doing what I expect of it.

Incidentally, should a 'six-month' embarrassment appear, the test-suite
will still be available - and will continue to ensure any future 'fixes'
don't cause similar regression-errors!)

* in fact, the tests were written before the code - but considering
all-else I'm throwing at you, "Test-Driven Development" may be one
(slightly less-topical) reference, too many

There has been plenty of research into the cost of errors. All really
boil-down to the idea that the 'later' an error is discovered, the more
expensive will be 'the fix'!

There are many 'guides' claiming to know how long is the 'right' length
for a function/procedure/block of code. However, the number of lines of
code in a function is no guide to its complexity. A list-comprehension
might fit into one line of code, but it is more complex than its two,
three, or even four line 'basic' equivalent. A better measure is "McCabe
Complexity" which is like establishing a 'reading level' for code
(instead of books for children of different ages/language abilities).
The wider term is "Cyclomatic Complexity".

Cyclomatic Complexity measures the number of coding-constructs there are
in a unit of code, eg if statements, loops, etc. The more there are, the
more logical 'paths' exist between 'start' and 'end'. This is the
concern of your static-test tool. The more paths, the harder it is to
test that each possibility has been tested/checked/proven, and the more
combinations of events and conditions that must (all?) be considered.
Here we can mention the KISS principle (not a principle of programming
per-se). Nuff said?


Earlier the idea of naming a chunk of code was mentioned. "Chunking" is
a term from psychology. It is a unit of thought. When coding a routine,
that unit might be a single line-of-code (it will vary with experience
and expertise). When a bunch of lines can be wrapped up into a single
unit - and that unit named, now we have a much larger 'chunk', and
reduced psychological/mental effort to remember what it does and where
it 'fits in'!

A related thought: If an author cannot describe what a section of code
is doing, there's a problem no amount of Python will fix!

If that name includes a conjunction such as "and", eg "choose which row
and wipe its data", then this indicates (at least to this author) that
the function is trying to do (two) too much. This assessment comes from
a programming ideal known as SRP - the "Single Responsibility
Principle". The idea that a piece of code has one objective also means
that it becomes much easier to locate where in a mass of code a problem
is likely to have arisen. It also makes the block very easy to test -
either it does ("what it says on ...") or it fails!

There are also ComSc concepts of "dependent" and "independent" linkages.
If code-unit "b" can't run unless unit "a" has previously executed,
these two are not independent. Certainly "b" is not "reusable" as and by
itself! High dependence is one enemy of "testability" and thus probably
also maintainability, etc, etc.

Think about list.append(). It does require that there is a list, and
some data to add - but they are inputs, not dependencies. It will add
what is 'input' to what is there already. There is no requirement that
the list be anything more than an empty list. Similarly, there is no
problem if the list already contains many, many items. The 'new stuff'
is added to the existing 'end' of the list. There is no requirement that
we tell the list how long it is - and thus 'where' to add the new stuff.
So, we can use list.append() without first using Len( list ). Similarly,
if a unit of code performs some action on one or more of the rows of
your data, does it need to know of previous calculations or arrangements
performed on those rows of data previously? Probably not - and if it
currently does, the code can likely be rearranged to obviate such
dependence.

Now, before dreams of nirvana over-take us, the cyclomatic complexity
and/or a replacement concept still exists in the way one must network or
'stitch-together' all of the smaller code-modules. However, (back to
"chunking") if one has a function called "search_row_for_palindromes()",
the thinking required to fit that into a series of similarly well-named
routines takes place at a much 'higher level' of problem-solving, than
the thought-processes involved in writing an if-statement inside a
for-loop which calls a palindrome-detection function!

Which all goes to show: there's no silver bullet!


(I'll leave you to research the topics-mentioned that may interest you,
as you see fit...)
-- 
Regards,
=dn

From cs at cskk.id.au  Sun Nov 28 06:00:41 2021
From: cs at cskk.id.au (Cameron Simpson)
Date: Sun, 28 Nov 2021 22:00:41 +1100
Subject: [Tutor] pylint(too-many-nested-blocks)
In-Reply-To: <2c34791d-dc21-4070-82d2-1c98d67616ce@gmail.com>
References: <2c34791d-dc21-4070-82d2-1c98d67616ce@gmail.com>
Message-ID: <YaNhWXZh9lhVs6Ci@cskk.homeip.net>

On 28Nov2021 14:51, Phil <phillor9 at gmail.com> wrote:
>"https://pycodequ.al/docs/pylint-messages/r1702-too-many-nested-blocks.html" 
>describes this error as:
>
>"Used when a function or method has too many nested blocks. This makes 
>the code less understandable and maintainable."
>
>The following is one of several functions that fits this description 
>and I'm wondering how I might reduce the number of for-loops. If the 
>number of for-loops cannot be reduced then I suppose the function 
>should be broken up into smaller functions. The problem is, as I see 
>it, little of the code is reusable in other functions that also have 
>too many nested blocks.

Remember that a linter is a large collection of guidelines when it comes 
to things like "too many". You could break this function up, but it 
doesn't seem unreasonable to me.

When I lint I'm making an informed decision about the linter's 
complaints. If you're happy that the function is sensible, you can do 
this:

    # pylint: disable=too-many-nested-blocks
    def pointingPairRow(self):

for that specific function.

My goal with a linter is clean output (no complaints). Oftne I ifx 
things to make it happy - these checks are generally sensble - but 
sometimes you know better than the linter, and pylint's disable comments 
come in very useful there.

Why silence? So that _new_ messages are worth checking out and are not 
buried in a sea of things I've already considered.

Cheers,
Cameron Simpson <cs at cskk.id.au>

From marcus.luetolf at bluewin.ch  Sun Nov 28 14:14:08 2021
From: marcus.luetolf at bluewin.ch (marcus.luetolf at bluewin.ch)
Date: Sun, 28 Nov 2021 20:14:08 +0100
Subject: [Tutor] computation problem
Message-ID: <004001d7e48c$1e900bb0$5bb02310$@bluewin.ch>

Hello Experts

 

I'd like to write a python code to find all possible combinations of a list
of n items.

If, for example, a list L consists of 4 items, n = 4,  L = ['abcd'], the
code should print out 24 different combinations from ['abcd'] to ...['dcba']

 

I tried several solutions posted on stackoverflow  using itertools  but none
gave the sought for combinations.

 

I'm aware the complexity of a a code using for loops might be exponential .

 

Could anybody tell me a text or tutorial how to approach tist task by python
?

 

 


From mats at wichmann.us  Sun Nov 28 14:17:59 2021
From: mats at wichmann.us (Mats Wichmann)
Date: Sun, 28 Nov 2021 12:17:59 -0700
Subject: [Tutor] pylint(too-many-nested-blocks)
In-Reply-To: <2c34791d-dc21-4070-82d2-1c98d67616ce@gmail.com>
References: <2c34791d-dc21-4070-82d2-1c98d67616ce@gmail.com>
Message-ID: <d58fc55b-eeda-248c-85bf-2a32d249e9d3@wichmann.us>

On 11/27/21 20:51, Phil wrote:
> "https://pycodequ.al/docs/pylint-messages/r1702-too-many-nested-blocks.html" 
> describes this error as:
> 
> "Used when a function or method has too many nested blocks. This makes 
> the code less understandable and maintainable."
> 
> The following is one of several functions that fits this description and 
> I'm wondering how I might reduce the number of for-loops. If the number 
> of for-loops cannot be reduced then I suppose the function should be 
> broken up into smaller functions. The problem is, as I see it, little of 
> the code is reusable in other functions that also have too many nested 
> blocks.
...
> The function works and so it's logically correct but it's messy and 
> inefficient.
> 

Just on the pylint topic in general: pylint is intended to be tuned so 
that it's useful for your project, there's no expectation that it's 
perfect for every project out of the box.

If it made you think, and you agree with it that something is hard to 
read because of many levels of nesting, then sure, think about how you 
could refactor. You don't have to do that right away.

Of the different levels of commentary from pylint, this complaint is 
probably at the least critical level.  There are EXXXX errors, WXXXX 
warnings and RXXXX recommendations. Yours is an 'R'.  Take that for 
whatever it's worth...

You can make a .pylintrc file - there's an option to dump a default and 
then you tune it to turn on/off things as you like.  I'm not fond of 
using this option too much - and especially not without commenting - and 
you lose track of *why*.  Or you can put as comments in your code 
stanzas to quiet pylint on specific areas of complaint. This is usually 
better, because you've noted in the exact location of the compliant that 
"yes I mean it".  If you want to "yes I'm happy with this for now, but 
want to revisit later" you can add a TODO comment to that effect as well.

If you have really special cases, you can write pylint plugins that 
handle your situation. Usually, though, this is to check more, not less, 
though I've actually used it to define some accepted names inside a 
program as a nicer way of quieting pylint grumbles about non-PEP8 naming 
choices - I don't turn off the whole warning class, but say that this 
specific set is accepted.

Many follow a model (I wish I could with my big project!) of getting 
pylint down to silence through fixes and settings and exclusions. That 
way you have a very clear notice when a change introduces a new warning 
- in other words, you get yourself to where you're only looking at deltas.


From mats at wichmann.us  Sun Nov 28 14:30:42 2021
From: mats at wichmann.us (Mats Wichmann)
Date: Sun, 28 Nov 2021 12:30:42 -0700
Subject: [Tutor] computation problem
In-Reply-To: <004001d7e48c$1e900bb0$5bb02310$@bluewin.ch>
References: <004001d7e48c$1e900bb0$5bb02310$@bluewin.ch>
Message-ID: <5d6108bd-ae30-0c3d-b017-acaa587ebcd2@wichmann.us>

On 11/28/21 12:14, marcus.luetolf at bluewin.ch wrote:
> Hello Experts
> 
>   
> 
> I'd like to write a python code to find all possible combinations of a list
> of n items.
> 
> If, for example, a list L consists of 4 items, n = 4,  L = ['abcd'], the
> code should print out 24 different combinations from ['abcd'] to ...['dcba']
> 
>   
> 
> I tried several solutions posted on stackoverflow  using itertools  but none
> gave the sought for combinations.
> 
>   
> 
> I'm aware the complexity of a a code using for loops might be exponential .
> 
>   
> 
> Could anybody tell me a text or tutorial how to approach tist task by python
> ?
> 

maybe if you showed what you've tried, and showed why itertools doesn't 
work for you...

['abcd'] isn't a list of four items, it's a list of one item.  If you 
want to treat the characters in the string as separate items, you have 
to break it apart and, if you want it displayed like you indicate above, 
combine it back together again. Do you know how to do that?

itertools.permutations will definitely do the "heavy lifting" for you.

 >>> from itertools import permutations
 >>> len(list(permutations(['a', 'b', 'c', 'd'])))
24

the list() is because permutations returns an iterator, not a list. 
Normally you'd end up iterating over the result, which is why it doesn't 
take the time to force it to a list itself.


From breamoreboy at gmail.com  Sun Nov 28 14:34:23 2021
From: breamoreboy at gmail.com (Mark Lawrence)
Date: Sun, 28 Nov 2021 19:34:23 +0000
Subject: [Tutor] computation problem
In-Reply-To: <004001d7e48c$1e900bb0$5bb02310$@bluewin.ch>
References: <004001d7e48c$1e900bb0$5bb02310$@bluewin.ch>
Message-ID: <412a1016-3310-853d-7f07-6a748cb3b522@gmail.com>

On 28/11/2021 19:14, marcus.luetolf at bluewin.ch wrote:
> Hello Experts
> 
>   
> 
> I'd like to write a python code to find all possible combinations of a list
> of n items.
> 
> If, for example, a list L consists of 4 items, n = 4,  L = ['abcd'], the
> code should print out 24 different combinations from ['abcd'] to ...['dcba']
> 
> I tried several solutions posted on stackoverflow  using itertools  but none
> gave the sought for combinations.
> 
> I'm aware the complexity of a a code using for loops might be exponential .
> 
> Could anybody tell me a text or tutorial how to approach tist task by python
> ?
> 

You have a list which contains one item, a string 'abcd'.  If you only 
want the string used the following works.

python3.9
Python 3.9.7 (default, Sep 10 2021, 14:59:43)
[GCC 11.2.0] on linux
Type "help", "copyright", "credits" or "license" for more information.
 >>> from itertools import permutations

 >>> l='abcd'
 >>> for a in permutations(l):print(a)
...
('a', 'b', 'c', 'd')
('a', 'b', 'd', 'c')
('a', 'c', 'b', 'd')
('a', 'c', 'd', 'b')
('a', 'd', 'b', 'c')
('a', 'd', 'c', 'b')
('b', 'a', 'c', 'd')
('b', 'a', 'd', 'c')
('b', 'c', 'a', 'd')
('b', 'c', 'd', 'a')
('b', 'd', 'a', 'c')
('b', 'd', 'c', 'a')
('c', 'a', 'b', 'd')
('c', 'a', 'd', 'b')
('c', 'b', 'a', 'd')
('c', 'b', 'd', 'a')
('c', 'd', 'a', 'b')
('c', 'd', 'b', 'a')
('d', 'a', 'b', 'c')
('d', 'a', 'c', 'b')
('d', 'b', 'a', 'c')
('d', 'b', 'c', 'a')
('d', 'c', 'a', 'b')
('d', 'c', 'b', 'a')
 >>>

-- 
My fellow Pythonistas, ask not what our language can do for you, ask
what you can do for our language.

Mark Lawrence


From cs at cskk.id.au  Sun Nov 28 18:24:26 2021
From: cs at cskk.id.au (Cameron Simpson)
Date: Mon, 29 Nov 2021 10:24:26 +1100
Subject: [Tutor] Enable Python feature in vim editor
In-Reply-To: <CAD7Ssm_V7wec-tRMWB5AZrbZXUydwvxpCaem6x-0OgqrcV_50w@mail.gmail.com>
References: <CAD7Ssm_V7wec-tRMWB5AZrbZXUydwvxpCaem6x-0OgqrcV_50w@mail.gmail.com>
Message-ID: <YaQPqhpHjfAzGQsQ@cskk.homeip.net>

On 24Nov2021 22:45, Kaushal Shriyan <kaushalshriyan at gmail.com> wrote:
>I am running CentOS Linux release 7.9.2009 (Core) and have enabled 
>below
>entry in .vimrc file
>
>$cat .vimrc
>set shiftwidth=2
>set shiftround
>set tabstop=4
>set softtabstop=4
>set noexpandtab
>set number
>set ruler
>set noautoindent
>set nosmartindent
>set noincsearch
>syntax enable
>$
>
>when i do vim testpythonscript.py I am facing the below Pymode error
>
>$vim testpythonscript.py
>
>[Pymode]: error: Pymode requires vim compiled with +python3 (exclusively).
>Most of features will be disabled.

This means that the vim you're invoking does not have the "python3" 
feature compiled into it. Indeed, in the `vim --version` output you 
include there is this:

    $vim --version
    VIM - Vi IMproved 7.4 (2013 Aug 10, compiled Dec 15 2020 16:44:08)
    Included patches: 1-207, 209-629
    Modified by <bugzilla at redhat.com>
    Compiled by <bugzilla at redhat.com>
    Huge version without GUI.  Features included (+) or not (-):
    [...]
    +cryptv          +linebreak       +python/dyn      +viminfo
    +cscope          +lispindent      -python3         +vreplace
    [...]

So you can see that "python3" has been omitted from that build.

Do a "yum search vim" and see if there is a vim variant with "python3" 
included (I haven't got a Centos host available to me). You could try 
replacing the installed vim with the python3 enabled vim if that is 
available.

Cheers,
Cameron Simpson <cs at cskk.id.au>

From genichka at gmail.com  Sun Nov 28 17:59:24 2021
From: genichka at gmail.com (Zhenya Sakal)
Date: Sun, 28 Nov 2021 17:59:24 -0500
Subject: [Tutor] computation problem
In-Reply-To: <412a1016-3310-853d-7f07-6a748cb3b522@gmail.com>
References: <004001d7e48c$1e900bb0$5bb02310$@bluewin.ch>
 <412a1016-3310-853d-7f07-6a748cb3b522@gmail.com>
Message-ID: <CALJrChujF7HiYxuLLEGE-bESaTFJwRnq57gO_4cn3-Z1aRN93Q@mail.gmail.com>

Hello!
You are looking into creating a powerset. There are many solutions to this
problem but I think the one through bit notation is the shortest.
def powerSet(items):
    N = len(items)
    # enumerate the 2 ** N possible combinations
    for i in range(2 ** N):
         combo = []
         for j in range(N):
              #test bit j-th of integer i -> that is turning base 10 into
binary for i
              if (i >> j) % 2 == 1:
                  combo.append(items[j])
         yield combo







On Sun, Nov 28, 2021 at 4:49 PM Mark Lawrence <breamoreboy at gmail.com> wrote:

> On 28/11/2021 19:14, marcus.luetolf at bluewin.ch wrote:
> > Hello Experts
> >
> >
> >
> > I'd like to write a python code to find all possible combinations of a
> list
> > of n items.
> >
> > If, for example, a list L consists of 4 items, n = 4,  L = ['abcd'], the
> > code should print out 24 different combinations from ['abcd'] to
> ...['dcba']
> >
> > I tried several solutions posted on stackoverflow  using itertools  but
> none
> > gave the sought for combinations.
> >
> > I'm aware the complexity of a a code using for loops might be
> exponential .
> >
> > Could anybody tell me a text or tutorial how to approach tist task by
> python
> > ?
> >
>
> You have a list which contains one item, a string 'abcd'.  If you only
> want the string used the following works.
>
> python3.9
> Python 3.9.7 (default, Sep 10 2021, 14:59:43)
> [GCC 11.2.0] on linux
> Type "help", "copyright", "credits" or "license" for more information.
>  >>> from itertools import permutations
>
>  >>> l='abcd'
>  >>> for a in permutations(l):print(a)
> ...
> ('a', 'b', 'c', 'd')
> ('a', 'b', 'd', 'c')
> ('a', 'c', 'b', 'd')
> ('a', 'c', 'd', 'b')
> ('a', 'd', 'b', 'c')
> ('a', 'd', 'c', 'b')
> ('b', 'a', 'c', 'd')
> ('b', 'a', 'd', 'c')
> ('b', 'c', 'a', 'd')
> ('b', 'c', 'd', 'a')
> ('b', 'd', 'a', 'c')
> ('b', 'd', 'c', 'a')
> ('c', 'a', 'b', 'd')
> ('c', 'a', 'd', 'b')
> ('c', 'b', 'a', 'd')
> ('c', 'b', 'd', 'a')
> ('c', 'd', 'a', 'b')
> ('c', 'd', 'b', 'a')
> ('d', 'a', 'b', 'c')
> ('d', 'a', 'c', 'b')
> ('d', 'b', 'a', 'c')
> ('d', 'b', 'c', 'a')
> ('d', 'c', 'a', 'b')
> ('d', 'c', 'b', 'a')
>  >>>
>
> --
> My fellow Pythonistas, ask not what our language can do for you, ask
> what you can do for our language.
>
> Mark Lawrence
>
> _______________________________________________
> Tutor maillist  -  Tutor at python.org
> To unsubscribe or change subscription options:
> https://mail.python.org/mailman/listinfo/tutor
>


-- 
Ievgeniia Sakal, PhD
she/her/hers,
Yale University,
Department of History

From tariqkhasiri at gmail.com  Sun Nov 28 18:03:59 2021
From: tariqkhasiri at gmail.com (Tariq Khasiri)
Date: Mon, 29 Nov 2021 05:03:59 +0600
Subject: [Tutor] Explanation of smote and upsampling
Message-ID: <CAFy_oHB4rbipBSchYveUCGH=YCNa472vkcDGy1B8BKZc6xFrwg@mail.gmail.com>

???

oversample = SMOTE()X, y =
oversample.fit_resample(c_data[c_data.columns[1:]],
c_data[c_data.columns[0]])usampled_df = X.assign(Churn = y)


???


Does this portion of code mean that I am upsampling column 0 and
column 1 of my data frame ( c_data ) ? Please kindly advise. Not
understanding this part of code ?????->  c_data[c_data.columns[1:]

From manpritsinghece at gmail.com  Sun Nov 28 20:53:17 2021
From: manpritsinghece at gmail.com (Manprit Singh)
Date: Mon, 29 Nov 2021 07:23:17 +0530
Subject: [Tutor] Multi threading and I/O bound process
Message-ID: <CAO1OCwY2eTxDrksO1gvrGYyDAzUMfDsf3mfiib6P6Q4YXsLYRg@mail.gmail.com>

Dear sir,

Just need to know if the below example is a correct example of
multithreading used with I/O bound process :

1) Without multi threading

import time
import urllib.request
# a function to dsplay first 25 bytes of a webpage
def readpage(urladd):
    with urllib.request.urlopen(urladd) as fobj:
        print(fobj.read(25))

t0 = time.time()
for _ in range(6):
    readpage("https://www.xyz.com/")
t1 = time.time()
print(t1-t0)
will display the first 25 bytes of the webpage  6 times in a sequential
order. and measure the time

2) Multithreading Using constructor   :

t0= time.time()
import threading
threadsgrp = []
for _ in range(6):
    thread = threading.Thread(target=readpage,args=("https://www.xyz.com/
",))
    threadsgrp.append(thread)
    thread.start()
for th in threadsgrp:
    th.join()
t1 =time.time()
print(t1-t0)

3)  Multithreading using subclass :

t1 = time.time()
class Techlivethread(threading.Thread):
    def __init__(self, add):
        threading.Thread.__init__(self)
        self.add = add
    def run(self):
        readpage(self.add)

grp =[]
for _ in range(6):
    th1 = Techlivethread("https://www.xyz.com/")
    grp.append(th1)
    th1.start()
for ele in grp:
    ele.join()
t2 = time.time()
print(t2-t1)

Kindly comment

From alexkleider at gmail.com  Sun Nov 28 21:10:46 2021
From: alexkleider at gmail.com (Alex Kleider)
Date: Sun, 28 Nov 2021 18:10:46 -0800
Subject: [Tutor] Enable Python feature in vim editor
In-Reply-To: <YaQPqhpHjfAzGQsQ@cskk.homeip.net>
References: <CAD7Ssm_V7wec-tRMWB5AZrbZXUydwvxpCaem6x-0OgqrcV_50w@mail.gmail.com>
 <YaQPqhpHjfAzGQsQ@cskk.homeip.net>
Message-ID: <CAMCEyD5jxg-kyhjyMPhH1txo2nRhpSz_sN3rUix6QH2SLuhx2Q@mail.gmail.com>

Interesting (re python3 'in vim')
I'm running Debian (current stable release- #11 I believe it is, and
'my vim' (vi is installed by default but to get vim requires apt install
vim) seems to have it included...
(p10) alex at X1:~/Notes/Py$ vim --version | grep python
+comments          +libcall           -python            +visualextra
+conceal           +linebreak         +python3           +viminfo
.........


On Sun, Nov 28, 2021 at 3:25 PM Cameron Simpson <cs at cskk.id.au> wrote:

> On 24Nov2021 22:45, Kaushal Shriyan <kaushalshriyan at gmail.com> wrote:
> >I am running CentOS Linux release 7.9.2009 (Core) and have enabled
> >below
> >entry in .vimrc file
> >
> >$cat .vimrc
> >set shiftwidth=2
> >set shiftround
> >set tabstop=4
> >set softtabstop=4
> >set noexpandtab
> >set number
> >set ruler
> >set noautoindent
> >set nosmartindent
> >set noincsearch
> >syntax enable
> >$
> >
> >when i do vim testpythonscript.py I am facing the below Pymode error
> >
> >$vim testpythonscript.py
> >
> >[Pymode]: error: Pymode requires vim compiled with +python3 (exclusively).
> >Most of features will be disabled.
>
> This means that the vim you're invoking does not have the "python3"
> feature compiled into it. Indeed, in the `vim --version` output you
> include there is this:
>
>     $vim --version
>     VIM - Vi IMproved 7.4 (2013 Aug 10, compiled Dec 15 2020 16:44:08)
>     Included patches: 1-207, 209-629
>     Modified by <bugzilla at redhat.com>
>     Compiled by <bugzilla at redhat.com>
>     Huge version without GUI.  Features included (+) or not (-):
>     [...]
>     +cryptv          +linebreak       +python/dyn      +viminfo
>     +cscope          +lispindent      -python3         +vreplace
>     [...]
>
> So you can see that "python3" has been omitted from that build.
>
> Do a "yum search vim" and see if there is a vim variant with "python3"
> included (I haven't got a Centos host available to me). You could try
> replacing the installed vim with the python3 enabled vim if that is
> available.
>
> Cheers,
> Cameron Simpson <cs at cskk.id.au>
> _______________________________________________
> Tutor maillist  -  Tutor at python.org
> To unsubscribe or change subscription options:
> https://mail.python.org/mailman/listinfo/tutor
>

From alan.gauld at yahoo.co.uk  Mon Nov 29 09:03:43 2021
From: alan.gauld at yahoo.co.uk (Alan Gauld)
Date: Mon, 29 Nov 2021 14:03:43 +0000
Subject: [Tutor] Explanation of smote and upsampling
In-Reply-To: <CAFy_oHB4rbipBSchYveUCGH=YCNa472vkcDGy1B8BKZc6xFrwg@mail.gmail.com>
References: <CAFy_oHB4rbipBSchYveUCGH=YCNa472vkcDGy1B8BKZc6xFrwg@mail.gmail.com>
Message-ID: <so2mk0$15k$1@ciao.gmane.io>

On 28/11/2021 23:03, Tariq Khasiri wrote:
> ???
> 
> oversample = SMOTE()X, y =
> oversample.fit_resample(c_data[c_data.columns[1:]],
> c_data[c_data.columns[0]])usampled_df = X.assign(Churn = y)
> 
> 
> ???
> 
> 
> Does this portion of code mean that I am upsampling column 0 and
> column 1 of my data frame ( c_data ) ? Please kindly advise. Not
> understanding this part of code ?????->  c_data[c_data.columns[1:]


It helps if you tell us what libraries you are using.
This list is really for questions about the core language
and standard library. Anything extra needs some explanation.

Reformatting your code as I think it should be...

oversample = SMOTE()
X, y = oversample.fit_resample(
                      c_data[c_data.columns[1:]],
                      c_data[c_data.columns[0]]
                      )
usampled_df = X.assign(Churn = y)

As to the part you don't understand, that will largely depend on the
definition of c_data, which I assume is an instance of a class
in your library? But without knowing the library we can only
guess at what it does.

HTH
-- 
Alan G
Author of the Learn to Program web site
http://www.alan-g.me.uk/
http://www.amazon.com/author/alan_gauld
Follow my photo-blog on Flickr at:
http://www.flickr.com/photos/alangauldphotos



From alan.gauld at yahoo.co.uk  Mon Nov 29 09:22:27 2021
From: alan.gauld at yahoo.co.uk (Alan Gauld)
Date: Mon, 29 Nov 2021 14:22:27 +0000
Subject: [Tutor] Multi threading and I/O bound process
In-Reply-To: <CAO1OCwY2eTxDrksO1gvrGYyDAzUMfDsf3mfiib6P6Q4YXsLYRg@mail.gmail.com>
References: <CAO1OCwY2eTxDrksO1gvrGYyDAzUMfDsf3mfiib6P6Q4YXsLYRg@mail.gmail.com>
Message-ID: <so2nn9$hgf$1@ciao.gmane.io>

On 29/11/2021 01:53, Manprit Singh wrote:

> 1) Without multi threading
> 
> import time
> import urllib.request
> # a function to dsplay first 25 bytes of a webpage
> def readpage(urladd):
>     with urllib.request.urlopen(urladd) as fobj:
>         print(fobj.read(25))
> 
> t0 = time.time()

Note you start the timer just before the loop after
the intialisation and function definition...

> for _ in range(6):
>     readpage("https://www.xyz.com/")
> t1 = time.time()
> print(t1-t0)
> will display the first 25 bytes of the webpage  6 times in a sequential
> order. and measure the time
> 
> 2) Multithreading Using constructor   :
> 
> t0= time.time()

Here you include the thread import and all of the initialisatoion and
class/function definitions that that includes. Not really a fair
comparison, especially on such a small scale example where every mS is
significant.

> import threading
> threadsgrp = []
> for _ in range(6):
>     thread = threading.Thread(target=readpage,args=("https://www.xyz.com/
> ",))
>     threadsgrp.append(thread)
>     thread.start()
> for th in threadsgrp:
>     th.join()
> t1 =time.time()
> print(t1-t0)
> 
> 3)  Multithreading using subclass :
> 
> t1 = time.time()

And the same here, you are including the class definition
time in the total. The init/definition code should only
run once in your program so it is not representative of
the time that threading/non-threading takes in a real
work program where threading is called many times in
different places.

> class Techlivethread(threading.Thread):
>     def __init__(self, add):
>         threading.Thread.__init__(self)
>         self.add = add
>     def run(self):
>         readpage(self.add)

It would be more efficient to transfer the readpage
code into run() directly since all you do is call it.

> grp =[]
> for _ in range(6):
>     th1 = Techlivethread("https://www.xyz.com/")
>     grp.append(th1)
>     th1.start()
> for ele in grp:
>     ele.join()
> t2 = time.time()
> print(t2-t1)



-- 
Alan G
Author of the Learn to Program web site
http://www.alan-g.me.uk/
http://www.amazon.com/author/alan_gauld
Follow my photo-blog on Flickr at:
http://www.flickr.com/photos/alangauldphotos



From joao.oliveira at ufob.edu.br  Mon Nov 29 16:59:32 2021
From: joao.oliveira at ufob.edu.br (Joao Carlos Silva de Oliveira Matos)
Date: Mon, 29 Nov 2021 18:59:32 -0300
Subject: [Tutor] Send SOAP to Proxy
Message-ID: <CAN8ghrBK0Ri6yNGKtaxGD4+tOF7+c=kFZoL4Z-ep9Eji1ZBYFw@mail.gmail.com>

I've been trying to access a WSDL Service via a SOAP protocol. But first I
need to get to a proxy in my University because the server will only accept
it as a client.

I found Zeep as the main python library for this job. But I have not been
successful in my tries. I know that I should use "HTTP". Another important
note: IT from the University says my request are getting there as Web
Application, meanwhile other requests are labeled as SOAP.

I hope you could help me find a better way to write this script without
getting error 403.

These are some structures I've already tried:

#01
session = Session()

session.proxies = {
    'http': 'http://proxy-ip-adress:8080'
}

transport=Transport(session=session)
client = Client('http://webservice/path?wsdl', transport=transport)

result = client.service.getMethod('params')

print(result)
---------------------------------------------------------------------------------------------------------

#02
client = Client('http://proxy-ip-adress:8080/path?wsdl')

result = client.service.getMethod('params')

print(result)

I've also tried the transport docs from Transports ? Zeep 4.1.0
documentation (python-zeep.org)
<https://docs.python-zeep.org/en/master/transport.html> and I've tried
setting session.trust_env = False.
-- 
[image: Ficheiro:Bras?o da UFOB.png ? Wikip?dia, a enciclop?dia livre]
Jo?o Carlos Silva de Oliveira Matos
Bolsista de Inova??o e Tecnologia
PROFNIT - Centro das Humanidades - UFOB
Mat. 2020100150

From marjababernard at gmail.com  Mon Nov 29 19:01:04 2021
From: marjababernard at gmail.com (Bernard Marjaba)
Date: Mon, 29 Nov 2021 19:01:04 -0500
Subject: [Tutor] Error When Using CoolProp
In-Reply-To: <aa0f237d-5bbf-a545-7b22-52044e77fc31@wichmann.us>
References: <A6BACFB5-DEDD-47E4-8092-F42C1028A72B@gmail.com>
 <aa0f237d-5bbf-a545-7b22-52044e77fc31@wichmann.us>
Message-ID: <F26446B2-9E53-4E8B-98DD-789D02969724@gmail.com>

Hello,

Yeah sure I?m checking with them as well. Meanwhile, this is a purely python related error following what you suggested to me about installing the wheel package:

I tried installing the wheel package using 

(venv) Bernards-MacBook-Pro:Python Bernard$ pip install /Users/Bernard/Downloads/CoolProp-6.4.1-cp38-cp38-macosx_10_9_x86_64.whl

but it gave me this error

ERROR: CoolProp-6.4.1-cp38-cp38-macosx_10_9_x86_64.whl is not a supported wheel on this platform.

I assume this means that i need python 3.8 for this wheel to work, which I have. I typed python3 in terminal it gave me 3.8.10, i typed python3 in PyCharm and it gave me 3.9.5, how come? So i searched for python 3.9 in my MacBook and i couldn?t find any traces of it, except for in a project folder: /Users/Bernard/PycharmProjects/Isentropic SUS Model/venv/lib/python3.9

However, 3.8 exists in the Applications folder. Any idea how to remove all traces of 3.9?

Thanks and regards,
Bernard Marjaba
(514) 922-9807

> On Nov 24, 2021, at 6:53 PM, Mats Wichmann <mats at wichmann.us> wrote:
> 
> On 11/24/21 13:17, Bernard Marjaba wrote:
>> Hello
>> I am having trouble using CoolProp with python. I have macOS Big Sur 11.5.1 with python version 3.10.
>> import CoolProp.CoolProp as CP
>> is giving me the error ModuleNotFoundError: No module named ?CoolProp.CoolProp? because it is not installed. I am however using it with MATLAB with no issues. I assume each software has its own wrapper?
>> So I tried installing CoolProp using pip install coolprop, and got the following error:
>> Collecting coolprop
>>   Using cached CoolProp-6.4.1.tar.gz (12.9 MB)
>>   Preparing metadata (setup.py) ... done
>> Using legacy 'setup.py install' for coolprop, since package 'wheel' is not installed.
>> Installing collected packages: coolprop
>>     Running setup.py install for coolprop ... error
>>     ERROR: Command errored out with exit status 1:
>>      command: '/Users/Bernard/PycharmProjects/Isentropic SUS Model/venv/bin/python' -u -c 'import io, os, sys, setuptools, tokenize; sys.argv[0] = '"'"'/private/var/folders/1j/jv39r0t12cb4dhscxkdz97740000gn/T/pip-install-z5afcrzx/coolprop_6739af7137474652994855ae32a03dd4/setup.py'"'"'; __file__='"'"'/private/var/folders/1j/jv39r0t12cb4dhscxkdz97740000gn/T/pip-install-z5afcrzx/coolprop_6739af7137474652994855ae32a03dd4/setup.py'"'"';f = getattr(tokenize, '"'"'open'"'"', open)(__file__) if os.path.exists(__file__) else io.StringIO('"'"'from setuptools import setup; setup()'"'"');code = f.read().replace('"'"'\r\n'"'"', '"'"'\n'"'"');f.close();exec(compile(code, __file__, '"'"'exec'"'"'))' install --record /private/var/folders/1j/jv39r0t12cb4dhscxkdz97740000gn/T/pip-record-8453i4i7/install-record.txt --single-version-externally-managed --compile --install-headers '/Users/Bernard/PycharmProjects/Isentropic SUS Model/venv/include/site/python3.9/coolprop'
>>          cwd: /private/var/folders/1j/jv39r0t12cb4dhscxkdz97740000gn/T/pip-install-z5afcrzx/coolprop_6739af7137474652994855ae32a03dd4/
>>     Complete output (79 lines):
>>     xcrun: error: invalid active developer path (/Library/Developer/CommandLineTools), missing xcrun at: /Library/Developer/CommandLineTools/usr/bin/xcrun
>>     OSX build detected, targetting 10.9 using clang/gcc v0.0.
>>     Cython will not be used; cy_ext is cpp
>>     running install
>>     /Users/Bernard/PycharmProjects/Isentropic SUS Model/venv/lib/python3.9/site-packages/setuptools/command/install.py:34: SetuptoolsDeprecationWarning: setup.py install is deprecated. Use build and pip and other standards-based tools.
>>       warnings.warn(
>>     running build
>>     running build_py
>>     creating build
>>     creating build/lib.macosx-10.9-x86_64-3.9
>>     creating build/lib.macosx-10.9-x86_64-3.9/CoolProp
>>     copying CoolProp/constants.py -> build/lib.macosx-10.9-x86_64-3.9/CoolProp
>>     copying CoolProp/__init__.py -> build/lib.macosx-10.9-x86_64-3.9/CoolProp
>>     copying CoolProp/BibtexParser.py -> build/lib.macosx-10.9-x86_64-3.9/CoolProp
>>     copying CoolProp/HumidAirProp.py -> build/lib.macosx-10.9-x86_64-3.9/CoolProp
>>     copying CoolProp/State.py -> build/lib.macosx-10.9-x86_64-3.9/CoolProp
>>     creating build/lib.macosx-10.9-x86_64-3.9/CoolProp/tests
>>     copying CoolProp/tests/runner.py -> build/lib.macosx-10.9-x86_64-3.9/CoolProp/tests
>>     copying CoolProp/tests/test_plots.py -> build/lib.macosx-10.9-x86_64-3.9/CoolProp/tests
>>     copying CoolProp/tests/test_Props.py -> build/lib.macosx-10.9-x86_64-3.9/CoolProp/tests
>>     copying CoolProp/tests/__init__.py -> build/lib.macosx-10.9-x86_64-3.9/CoolProp/tests
>>     copying CoolProp/tests/test_CoolPropState.py -> build/lib.macosx-10.9-x86_64-3.9/CoolProp/tests
>>     creating build/lib.macosx-10.9-x86_64-3.9/CoolProp/GUI
>>     copying CoolProp/GUI/__init__.py -> build/lib.macosx-10.9-x86_64-3.9/CoolProp/GUI
>>     copying CoolProp/GUI/CoolPropGUI.py -> build/lib.macosx-10.9-x86_64-3.9/CoolProp/GUI
>>     copying CoolProp/GUI/PsychScript.py -> build/lib.macosx-10.9-x86_64-3.9/CoolProp/GUI
>>     creating build/lib.macosx-10.9-x86_64-3.9/CoolProp/Plots
>>     copying CoolProp/Plots/ConsistencyPlots_pcsaft.py -> build/lib.macosx-10.9-x86_64-3.9/CoolProp/Plots
>>     copying CoolProp/Plots/PsychChart.py -> build/lib.macosx-10.9-x86_64-3.9/CoolProp/Plots
>>     copying CoolProp/Plots/SimpleCycles.py -> build/lib.macosx-10.9-x86_64-3.9/CoolProp/Plots
>>     copying CoolProp/Plots/__init__.py -> build/lib.macosx-10.9-x86_64-3.9/CoolProp/Plots
>>     copying CoolProp/Plots/psy.py -> build/lib.macosx-10.9-x86_64-3.9/CoolProp/Plots
>>     copying CoolProp/Plots/Plots.py -> build/lib.macosx-10.9-x86_64-3.9/CoolProp/Plots
>>     copying CoolProp/Plots/Common.py -> build/lib.macosx-10.9-x86_64-3.9/CoolProp/Plots
>>     copying CoolProp/Plots/SimpleCyclesCompression.py -> build/lib.macosx-10.9-x86_64-3.9/CoolProp/Plots
>>     copying CoolProp/Plots/ConsistencyPlots.py -> build/lib.macosx-10.9-x86_64-3.9/CoolProp/Plots
>>     copying CoolProp/Plots/PsychScript.py -> build/lib.macosx-10.9-x86_64-3.9/CoolProp/Plots
>>     copying CoolProp/Plots/Tests.py -> build/lib.macosx-10.9-x86_64-3.9/CoolProp/Plots
>>     copying CoolProp/Plots/SimpleCyclesExpansion.py -> build/lib.macosx-10.9-x86_64-3.9/CoolProp/Plots
>>     copying CoolProp/typedefs.pxd -> build/lib.macosx-10.9-x86_64-3.9/CoolProp
>>     copying CoolProp/CoolProp.pxd -> build/lib.macosx-10.9-x86_64-3.9/CoolProp
>>     copying CoolProp/State.pxd -> build/lib.macosx-10.9-x86_64-3.9/CoolProp
>>     copying CoolProp/cAbstractState.pxd -> build/lib.macosx-10.9-x86_64-3.9/CoolProp
>>     copying CoolProp/constants_header.pxd -> build/lib.macosx-10.9-x86_64-3.9/CoolProp
>>     copying CoolProp/AbstractState.pxd -> build/lib.macosx-10.9-x86_64-3.9/CoolProp
>>     copying CoolProp/Plots/psyrc -> build/lib.macosx-10.9-x86_64-3.9/CoolProp/Plots
>>     running build_ext
>>     creating private
>>     creating private/var
>>     creating private/var/folders
>>     creating private/var/folders/1j
>>     creating private/var/folders/1j/jv39r0t12cb4dhscxkdz97740000gn
>>     creating private/var/folders/1j/jv39r0t12cb4dhscxkdz97740000gn/T
>>     creating private/var/folders/1j/jv39r0t12cb4dhscxkdz97740000gn/T/pip-install-z5afcrzx
>>     creating private/var/folders/1j/jv39r0t12cb4dhscxkdz97740000gn/T/pip-install-z5afcrzx/coolprop_6739af7137474652994855ae32a03dd4
>>     gcc -Wno-unused-result -Wsign-compare -Wunreachable-code -fno-common -dynamic -DNDEBUG -g -fwrapv -O3 -Wall -arch x86_64 -g -I/Users/Bernard/PycharmProjects/Isentropic SUS Model/venv/include -I/Library/Frameworks/Python.framework/Versions/3.9/include/python3.9 -c /private/var/folders/1j/jv39r0t12cb4dhscxkdz97740000gn/T/pip-install-z5afcrzx/coolprop_6739af7137474652994855ae32a03dd4/tmp0hdk2tsu.cpp -o private/var/folders/1j/jv39r0t12cb4dhscxkdz97740000gn/T/pip-install-z5afcrzx/coolprop_6739af7137474652994855ae32a03dd4/tmp0hdk2tsu.o
>>     xcrun: error: invalid active developer path (/Library/Developer/CommandLineTools), missing xcrun at: /Library/Developer/CommandLineTools/usr/bin/xcrun
>>     gcc -Wno-unused-result -Wsign-compare -Wunreachable-code -fno-common -dynamic -DNDEBUG -g -fwrapv -O3 -Wall -arch x86_64 -g -I/Users/Bernard/PycharmProjects/Isentropic SUS Model/venv/include -I/Library/Frameworks/Python.framework/Versions/3.9/include/python3.9 -c /private/var/folders/1j/jv39r0t12cb4dhscxkdz97740000gn/T/pip-install-z5afcrzx/coolprop_6739af7137474652994855ae32a03dd4/tmp0r3vfej0.cpp -o private/var/folders/1j/jv39r0t12cb4dhscxkdz97740000gn/T/pip-install-z5afcrzx/coolprop_6739af7137474652994855ae32a03dd4/tmp0r3vfej0.o
>>     xcrun: error: invalid active developer path (/Library/Developer/CommandLineTools), missing xcrun at: /Library/Developer/CommandLineTools/usr/bin/xcrun
>>     gcc -Wno-unused-result -Wsign-compare -Wunreachable-code -fno-common -dynamic -DNDEBUG -g -fwrapv -O3 -Wall -arch x86_64 -g -I/Users/Bernard/PycharmProjects/Isentropic SUS Model/venv/include -I/Library/Frameworks/Python.framework/Versions/3.9/include/python3.9 -c /private/var/folders/1j/jv39r0t12cb4dhscxkdz97740000gn/T/pip-install-z5afcrzx/coolprop_6739af7137474652994855ae32a03dd4/tmp93394q_4.cpp -o private/var/folders/1j/jv39r0t12cb4dhscxkdz97740000gn/T/pip-install-z5afcrzx/coolprop_6739af7137474652994855ae32a03dd4/tmp93394q_4.o
>>     xcrun: error: invalid active developer path (/Library/Developer/CommandLineTools), missing xcrun at: /Library/Developer/CommandLineTools/usr/bin/xcrun
>>     Adding these shared_ptr compilation macros: []
>>     building 'CoolProp.CoolProp' extension
>>     creating build/temp.macosx-10.9-x86_64-3.9
>>     creating build/temp.macosx-10.9-x86_64-3.9/CoolProp
>>     creating build/temp.macosx-10.9-x86_64-3.9/src
>>     creating build/temp.macosx-10.9-x86_64-3.9/src/Backends
>>     creating build/temp.macosx-10.9-x86_64-3.9/src/Backends/Cubics
>>     creating build/temp.macosx-10.9-x86_64-3.9/src/Backends/Helmholtz
>>     creating build/temp.macosx-10.9-x86_64-3.9/src/Backends/Helmholtz/Fluids
>>     creating build/temp.macosx-10.9-x86_64-3.9/src/Backends/IF97
>>     creating build/temp.macosx-10.9-x86_64-3.9/src/Backends/Incompressible
>>     creating build/temp.macosx-10.9-x86_64-3.9/src/Backends/PCSAFT
>>     creating build/temp.macosx-10.9-x86_64-3.9/src/Backends/REFPROP
>>     creating build/temp.macosx-10.9-x86_64-3.9/src/Backends/Tabular
>>     creating build/temp.macosx-10.9-x86_64-3.9/src/Tests
>>     gcc -Wno-unused-result -Wsign-compare -Wunreachable-code -fno-common -dynamic -DNDEBUG -g -fwrapv -O3 -Wall -arch x86_64 -g -I. -I./include -I./src -I./externals/Eigen -I./externals/fmtlib -I./externals/msgpack-c/include -I/Users/Bernard/PycharmProjects/Isentropic SUS Model/venv/include -I/Library/Frameworks/Python.framework/Versions/3.9/include/python3.9 -c CoolProp/CoolProp.cpp -o build/temp.macosx-10.9-x86_64-3.9/CoolProp/CoolProp.o
>>     xcrun: error: invalid active developer path (/Library/Developer/CommandLineTools), missing xcrun at: /Library/Developer/CommandLineTools/usr/bin/xcrun
>>     error: command '/usr/bin/gcc' failed with exit code 1
>>     ----------------------------------------
>> ERROR: Command errored out with exit status 1: '/Users/Bernard/PycharmProjects/Isentropic SUS Model/venv/bin/python' -u -c 'import io, os, sys, setuptools, tokenize; sys.argv[0] = '"'"'/private/var/folders/1j/jv39r0t12cb4dhscxkdz97740000gn/T/pip-install-z5afcrzx/coolprop_6739af7137474652994855ae32a03dd4/setup.py'"'"'; __file__='"'"'/private/var/folders/1j/jv39r0t12cb4dhscxkdz97740000gn/T/pip-install-z5afcrzx/coolprop_6739af7137474652994855ae32a03dd4/setup.py'"'"';f = getattr(tokenize, '"'"'open'"'"', open)(__file__) if os.path.exists(__file__) else io.StringIO('"'"'from setuptools import setup; setup()'"'"');code = f.read().replace('"'"'\r\n'"'"', '"'"'\n'"'"');f.close();exec(compile(code, __file__, '"'"'exec'"'"'))' install --record /private/var/folders/1j/jv39r0t12cb4dhscxkdz97740000gn/T/pip-record-8453i4i7/install-record.txt --single-version-externally-managed --compile --install-headers '/Users/Bernard/PycharmProjects/Isentropic SUS Model/venv/include/site/python3.9/coolprop' Check the logs for full command output.
> 
> 
> looks like you probably don't have the command-line developer tools installed - it's separate from the main xcode install on MacOS.
> 
> also, you might be able to install without the effort to build if you installed the wheel package first - see this error from early on:
> 
> > Using legacy 'setup.py install' for coolprop, since package 'wheel' is not installed.
> 
> I have no idea what CoolProp is, never heard of it, but a check here:
> 
> https://pypi.org/project/CoolProp/#files <https://pypi.org/project/CoolProp/#files>
> 
> shows there *is* a macosx wheel available for installation - at least as long as you're using no newer than Python 3.8.  The project looks like it hasn't updated for a good long time so they haven't done anything for 3.9 or 3.10. That's probably cause for some worry...
> 
> You'd be far better asking this kind of thing directly to the project in question, we won't be able to answer any further stuff from here.


From manpritsinghece at gmail.com  Tue Nov 30 12:05:14 2021
From: manpritsinghece at gmail.com (Manprit Singh)
Date: Tue, 30 Nov 2021 22:35:14 +0530
Subject: [Tutor] __str__ Vs __repr__
Message-ID: <CAO1OCwYRWaTQpCHMtRCfNf3b0Pt8A8zLFmSY0XTM7OAkm8SQrw@mail.gmail.com>

Dear Sir,

After assigning a value to a variable, Lets say variable is a, and the
value assigned to it is 5,
On an interactive shell after writing a and then hitting Enter key, it
prints the value of a, that is 5, This happens due to __str__ or __repr__?

What should I use(__str__ or  __repr__) if I want something to be printed
when I print an object of a user defined class ?

From alexkleider at gmail.com  Tue Nov 30 12:53:45 2021
From: alexkleider at gmail.com (Alex Kleider)
Date: Tue, 30 Nov 2021 09:53:45 -0800
Subject: [Tutor] __str__ Vs __repr__
In-Reply-To: <CAO1OCwYRWaTQpCHMtRCfNf3b0Pt8A8zLFmSY0XTM7OAkm8SQrw@mail.gmail.com>
References: <CAO1OCwYRWaTQpCHMtRCfNf3b0Pt8A8zLFmSY0XTM7OAkm8SQrw@mail.gmail.com>
Message-ID: <CAMCEyD7r=Gh0BNcVYC4XrCKSZWLQebc9YTv3Bn3N+8ZbeTqbig@mail.gmail.com>

https://www.tutorialspoint.com/str-vs-repr-in-python

On Tue, Nov 30, 2021 at 9:06 AM Manprit Singh <manpritsinghece at gmail.com>
wrote:

> Dear Sir,
>
> After assigning a value to a variable, Lets say variable is a, and the
> value assigned to it is 5,
> On an interactive shell after writing a and then hitting Enter key, it
> prints the value of a, that is 5, This happens due to __str__ or __repr__?
>
> What should I use(__str__ or  __repr__) if I want something to be printed
> when I print an object of a user defined class ?
> _______________________________________________
> Tutor maillist  -  Tutor at python.org
> To unsubscribe or change subscription options:
> https://mail.python.org/mailman/listinfo/tutor
>

From wlfraed at ix.netcom.com  Tue Nov 30 12:58:43 2021
From: wlfraed at ix.netcom.com (Dennis Lee Bieber)
Date: Tue, 30 Nov 2021 12:58:43 -0500
Subject: [Tutor] __str__ Vs __repr__
References: <CAO1OCwYRWaTQpCHMtRCfNf3b0Pt8A8zLFmSY0XTM7OAkm8SQrw@mail.gmail.com>
Message-ID: <p5ocqgl6l7onhq7o4075psocebmeo7pe9l@4ax.com>

On Tue, 30 Nov 2021 22:35:14 +0530, Manprit Singh
<manpritsinghece at gmail.com> declaimed the following:

>After assigning a value to a variable, Lets say variable is a, and the
>value assigned to it is 5,
>On an interactive shell after writing a and then hitting Enter key, it
>prints the value of a, that is 5, This happens due to __str__ or __repr__?
>

	Using that same shell, you can easily determine which is used. Note
that __str__() formats "human readable" text, while __repr__() formats
"program" text.

PythonWin 3.8.2 (default, Aug 25 2020, 15:54:26) [MSC v.1900 64 bit
(AMD64)] on win32.
Portions Copyright 1994-2018 Mark Hammond - see 'Help/About PythonWin' for
further copyright information.
>>> a = 5
>>> a
5
>>> b = "5"
>>> b
'5'
>>> print(a, b)
5 5
>>> print(str(a), str(b))
5 5
>>> print (repr(a), repr(b))
5 '5'
>>> 

	Note how the sell displays b with quote marks -- which is what you get
when asking for repr() of a string object.

>What should I use(__str__ or  __repr__) if I want something to be printed
>when I print an object of a user defined class ?

	You would have to write a __str__() method to explicitly format some
form of the object for user output, or __repr__() for some form that might
be used in the code as a literal. Note that, for many classes, there is no
reasonable __repr__() that generates a literal that could be used in the
program -- hence why one often gets just text stating "class" (or "type")
instance "ID" (for common Python, memory address).

>>> class C():
... 	def __init__(self, arg):
... 		self.arg = arg
... 	def __repr__(self):
... 		return "Class C instance with arg = %r" % self.arg
... 	
>>> c1 = C(5)
>>> c2 = C("5")
>>> c1
Class C instance with arg = 5
>>> c2
Class C instance with arg = '5'
>>> 

	%r invokes repr() which invokes the object __repr__()
	%s invokes str() which invokes __str__() IF IT EXISTS, otherwise it
uses __repr__()

>>> str(c1)
'Class C instance with arg = 5'
>>> str(c2)
"Class C instance with arg = '5'"

	Note how str(c2) shows the quoted '5' which matches the repr() of the
object. Now, add a __str__() method using %s translation

>>> class D():
... 	def __init__(self, arg):
... 		self.arg = arg
... 	def __repr__(self):
... 		return "Class D instance with arg = %r" % self.arg
... 	def __str__(self):
... 		return "Class D instance with arg = %s" % self.arg
... 	
>>> d1 = D(5)
>>> d2 = D("6")
>>> d1
Class D instance with arg = 5
>>> d2
Class D instance with arg = '6'
>>> str(d1)
'Class D instance with arg = 5'
>>> str(d2)
'Class D instance with arg = 6'
>>> repr(d1)
'Class D instance with arg = 5'
>>> repr(d2)
"Class D instance with arg = '6'"
>>> 

	The shell still uses the repr() format, but str() uses the other
format, which doesn't add quotes.

>>> print(d1, d2)
Class D instance with arg = 5 Class D instance with arg = 6
>>> print(c1, c2)
Class C instance with arg = 5 Class C instance with arg = '5'
>>> 

	print() uses the __str__() form where possible, otherwise devolves to
__repr__() form.
>_______________________________________________
>Tutor maillist  -  Tutor at python.org
>To unsubscribe or change subscription options:
>https://mail.python.org/mailman/listinfo/tutor


-- 
	Wulfraed                 Dennis Lee Bieber         AF6VN
	wlfraed at ix.netcom.com    http://wlfraed.microdiversity.freeddns.org/


From phillor9 at gmail.com  Tue Nov 30 16:57:40 2021
From: phillor9 at gmail.com (Phil)
Date: Wed, 1 Dec 2021 08:57:40 +1100
Subject: [Tutor] pylint(too-many-nested-blocks)
In-Reply-To: <703ee90c-2d81-5ea3-91aa-7b2a399e4531@DancesWithMice.info>
References: <2c34791d-dc21-4070-82d2-1c98d67616ce@gmail.com>
 <703ee90c-2d81-5ea3-91aa-7b2a399e4531@DancesWithMice.info>
Message-ID: <c58dda6d-2da8-8993-787f-77b69314ecf4@gmail.com>

Thank you dn for taking the time to write a lengthy informative reply 
and thank you once again Cameron and Mats. I will endeavor to make good 
use of the advice given.
> Does Python itself see this as an error and stop working, or is it only
> the code-checker s/w?

It's not so much an error message, rather a recommendation and one that 
I feel that I should act on.

> Were we conducting a Code Review, this function would definitely attract
> criticism. You have already recognised the complexity, but seem somewhat
> satisfied - on the  grounds that the whole works.

I think I've only ever produced one application that was truly useful. 
My current project doesn't do anything that others cannot, it's just a 
my-way project and so I could leave it as it is or try to make it look 
more a work of art.


> Here's where things become rather subjective. You (no criticism) seem to
> have a mathematical view of programming,

Isn't computer programming a pursuit based on maths? Even so, I suppose 
the result doesn't need to look like a dog's breakfast.


> I have been criticised (but exhibit little remorse) for breaking things
> down into "smaller" units of code than others feel necessary.

I can see where I could split the function that I posted into two and 
one of those parts could be reused in a yet-to-be-written function. I do 
try to reuse code where I can. I'll need to give a lot more thought to 
how I might reduce the complexity.


> Now is a good time pick-up the testing tool's feedback: "understandable
> and maintainable". It's not merely a matter of
> "readability"/"understandability", but also maintainability - and that
> of the objectives of the tool: "testability".

I know that testing tools exist, however, I've always considered their 
use to be beyond the understanding of the neophyte especially this 
amateur programmer.


> Earlier the idea of naming a chunk of code was mentioned.

I find it difficult to come up with meaningful names for functions and 
even variables. I know that 'x' or 'y' is often a poor choice and I 
often leave them in place until I can think of something better. Often I 
don't and so they stay, and of course, I forget what they mean the next 
time I look at the code again.


> (I'll leave you to research the topics-mentioned that may interest you,
> as you see fit...)

I haven't spent anytime on the laptop or the Internet for the fast few 
days and so I haven't had a chance to study the topic of cylomatic 
complexity, however, I do have a Wikipedia page open and I will try to 
gain some understanding of it after I post this e-mail.

-- 

Regards,
Phil


From cs at cskk.id.au  Tue Nov 30 16:40:45 2021
From: cs at cskk.id.au (Cameron Simpson)
Date: Wed, 1 Dec 2021 08:40:45 +1100
Subject: [Tutor] Send SOAP to Proxy
In-Reply-To: <CAN8ghrBK0Ri6yNGKtaxGD4+tOF7+c=kFZoL4Z-ep9Eji1ZBYFw@mail.gmail.com>
References: <CAN8ghrBK0Ri6yNGKtaxGD4+tOF7+c=kFZoL4Z-ep9Eji1ZBYFw@mail.gmail.com>
Message-ID: <YaaaXYq3kE479ht1@cskk.homeip.net>

On 29Nov2021 18:59, Joao Carlos Silva de Oliveira Matos <joao.oliveira at ufob.edu.br> wrote:
>I've been trying to access a WSDL Service via a SOAP protocol. But first I
>need to get to a proxy in my University because the server will only accept
>it as a client.

Skipping the complexities of the library, if it is using the builtin 
Python libraries underneath I expect it to honour the normal environment 
variables $http_proxy and $https_proxy, meaning your code does not need 
to specify a proxy.

If you set these in your environment and try your code with no proxy 
specification in it, do things work?

Bourne shell syntax to set these:

    http_proxy='http://proxy-ip-adress:8080'
    https_proxy='http://proxy-ip-adress:8080'
    export http_proxy https_proxy

If you set them in your environment, do things work (provided you strip 
the settings out of the inline code itself i.e. comment out the 
"session.proxies" stuff?

Cheers,Cameron Simpson <cs at cskk.id.au>

From cs at cskk.id.au  Tue Nov 30 15:43:09 2021
From: cs at cskk.id.au (Cameron Simpson)
Date: Wed, 1 Dec 2021 07:43:09 +1100
Subject: [Tutor] __str__ Vs __repr__
In-Reply-To: <CAO1OCwYRWaTQpCHMtRCfNf3b0Pt8A8zLFmSY0XTM7OAkm8SQrw@mail.gmail.com>
References: <CAO1OCwYRWaTQpCHMtRCfNf3b0Pt8A8zLFmSY0XTM7OAkm8SQrw@mail.gmail.com>
Message-ID: <YaaM3Ufw+wfyrsqS@cskk.homeip.net>

On 30Nov2021 22:35, Manprit Singh <manpritsinghece at gmail.com> wrote:
>After assigning a value to a variable, Lets say variable is a, and the
>value assigned to it is 5,
>On an interactive shell after writing a and then hitting Enter key, it
>prints the value of a, that is 5, This happens due to __str__ or __repr__?

__repr__, because that generally provides greater detail. Ideally it 
provides text which you could run as a Python expression to get the 
value.

__str__ is intended for "normal output", whatever that means :-( The 
print() function calls __str__ on every object it prints. So when you 
go:

    print('foo')

you get a bare:

    foo

without any quotes. Generally an object's __str__ should be concise and 
not have much punctuation in it. It should make sense when the reader 
already knows what type of thing is being printed.

>What should I use(__str__ or  __repr__) if I want something to be printed
>when I print an object of a user defined class ?

That depends entirely on context, unfortunately. It isn't "what version 
should I print?" but "what version does the user want?"

If you're talking to an end user (instead of you, the programmer, at the 
interactive prompt) you probably want __str__ (because print() will do 
that for you automatically), and a better question is instead: what 
should __str__ return? Something concise and readable. __repr__ is for 
the programmer doing debugging.

Cheers,
Cameron Simpson <cs at cskk.id.au>

From PyTutor at DancesWithMice.info  Tue Nov 30 18:19:11 2021
From: PyTutor at DancesWithMice.info (dn)
Date: Wed, 1 Dec 2021 12:19:11 +1300
Subject: [Tutor] pylint(too-many-nested-blocks)
In-Reply-To: <c58dda6d-2da8-8993-787f-77b69314ecf4@gmail.com>
References: <2c34791d-dc21-4070-82d2-1c98d67616ce@gmail.com>
 <703ee90c-2d81-5ea3-91aa-7b2a399e4531@DancesWithMice.info>
 <c58dda6d-2da8-8993-787f-77b69314ecf4@gmail.com>
Message-ID: <34dc6d5f-99f7-7826-95f3-1e5965ddfb87@DancesWithMice.info>

On 01/12/2021 10.57, Phil wrote:
> Thank you dn for taking the time to write a lengthy informative reply
> and thank you once again Cameron and Mats. I will endeavor to make good
> use of the advice given.

Glad to hear it's helpful.

It is evident that there are plenty of other folk 'here', who read posts
which are not explicitly addressed to them, and who gain in some small,
or maybe, large way. That's one of the functions (hah!) and benefits of
the list.

(also, you can believe that I collect that these are re-worked and
become multi-purpose - ooh, somewhat similar to a Python function. Oh
boy, he's on-a-roll today, as you will see...)


>> Does Python itself see this as an error and stop working, or is it only
>> the code-checker s/w?
> 
> It's not so much an error message, rather a recommendation and one that
> I feel that I should act on.

Right answer!


>> Were we conducting a Code Review, this function would definitely attract
>> criticism. You have already recognised the complexity, but seem somewhat
>> satisfied - on the? grounds that the whole works.
> 
> I think I've only ever produced one application that was truly useful.
> My current project doesn't do anything that others cannot, it's just a
> my-way project and so I could leave it as it is or try to make it look
> more a work of art.

The "Ikea effect", like home-cooking*, is predicated largely on one's
feelings of satisfaction at accomplishment, over-riding other factors,
eg constructing an Ikea cot for baby, but only one side of the cot will
slide up-and-down its rails due to a construction error - but hey, I
built it with my own (?)fair hands!

* we had a rule in my student flat/'frat house' (last century) that "if
the cook eats the food, no-one else is allowed to complain".


OTOH, the non-practical pursuit of perfection leads to one never being
'finished'!


Where is your 'happy medium'?
(rhetorical question)


There are (apparently) employers who will look at your portfolio of work
(should you ever be applying for such a job), and thus it doesn't matter
whether you are repeating others' projects, or making one that is only
useful to yourself...

Then there is: "practice makes perfect"!


>> Here's where things become rather subjective. You (no criticism) seem to
>> have a mathematical view of programming,
> 
> Isn't computer programming a pursuit based on maths? Even so, I suppose
> the result doesn't need to look like a dog's breakfast.

Apologies, I suspected you'd fall into this pattern - and many others
'here' (and amongst your correspondents) will ask/challenge "and what's
wrong with that?".

Programming as a hobby may well be a solitary activity, but few
professionals work in-isolation (says he, who works in a country on the
opposite side of the world from all of his colleagues, whilst dealing
with folk from all corners of the globe*).

Accordingly, the line about code being read by humans! So, if you are
writing for humans, how mathematical do you expect us to be? (free
advice: don't expect it to be 'much')

Things only roll (rapidly) 'down-hill' from there: what about programs
being used by "users"? The 'mental model' that users have of any
computer system is almost certainly, and quite possibly,
radically-different to the way we 'see' it. If the authors want a system
to be used, this needs to be taken into account.

Now you've left Math way-behind, and are slogging through the slough of
"User Experience", ie Psychology and Sociology.


It may not matter in this case, indeed in any 'hobby' scenario. However,
good habits are by-definition "good" - and bad habits are hard to lose
("become vices")! Also, please recall that 'six month you' concept - a
human ex machina!


* gratuitous use of English-expression, with the possible outcome of
irritating mathematicians everywhere.
(Heh, heh, heh - cackle, cackle...)


>> I have been criticised (but exhibit little remorse) for breaking things
>> down into "smaller" units of code than others feel necessary.
> 
> I can see where I could split the function that I posted into two and
> one of those parts could be reused in a yet-to-be-written function. I do
> try to reuse code where I can. I'll need to give a lot more thought to
> how I might reduce the complexity.

As mentioned, "re-use" is not the only justification for
building/abstracting code away and into a function.

I'm currently reviewing "Learn Python Programming, 2nd Edn" by Fabrizio
Romano, Packt, 2018. Chapter 4 is entitled "Functions, the Building
Blocks of Code". After the chapter-intro, he invites us to consider:
"Why use functions?". Here are his answers:-

- they reduce code duplication in a program... [exactly what I was first
taught back in the days of "spaghetti code" and "monolithic programs"]

- they help in splitting a complex task or procedure into smaller
blocks, each of which becomes a function [you may have read something
similar, recently]

- they hide the implementation details from their users [I didn't
introduce the term "Information/Implementation Hiding" before - you
had/still have enough to catch-up on. That said, it is an important
concept, following-on from the previous point]

- they improve traceability [another word related to debugging and testing]

- they improve readability ['nuff said]

(the chapter thereafter details each of these points)

NB I'm not recommending the book (haven't read it (all) yet!) per-se,
simply taking-advantage of the serendipitous opportunity.

It may be worth your while to purchase a (reasonably-recent) text-book,
to give you some guide - what we call a "learning path"!

Incidentally, there's an impression that you've adopted a 'grey gypsy'
life-style. However, if you can gain decent Internet access, perhaps an
online course might confer similar additional/alternate benefit?


>> Now is a good time pick-up the testing tool's feedback: "understandable
>> and maintainable". It's not merely a matter of
>> "readability"/"understandability", but also maintainability - and that
>> of the objectives of the tool: "testability".
> 
> I know that testing tools exist, however, I've always considered their
> use to be beyond the understanding of the neophyte especially this
> amateur programmer.

Well then, you can color me impressed, that you are using any such
'testing tool' at all. Few trainees see the need (a direct consequence
of trainers' employing 'toy examples' which are short and easily(?)
digested - but quite unlike 'real life' - and as such, the "need" for
much beyond the 'mathematical side' of programming is not adequately
established!)

I cheerfully blather-on about pytest and TDD. Some of the irritation is
(that I'm irritating) because folk don't like to have un-learn/re-learn
'stuff'! It's hard work - and harder than learning something for 'the
first time'!


Are you using an IDE such as PyCharm or Codium (the F/LOSS-y alternative
to VS-Code)? If so, there are plenty of "linters" (as others mentioned
earlier) and other learning-tools. I'm keen on Sourcery (British, hence
the spelling) which spots opportunities to show how things could be
better-expressed and/or accomplished more efficiently or more
'pythonically'.

That said, add too many of these tools, and you will quickly feel
overwhelmed by the volume of 'feedback'. Hence YMMV!


>> Earlier the idea of naming a chunk of code was mentioned.
> 
> I find it difficult to come up with meaningful names for functions and
> even variables. I know that 'x' or 'y' is often a poor choice and I
> often leave them in place until I can think of something better. Often I
> don't and so they stay, and of course, I forget what they mean the next
> time I look at the code again.

Welcome to the club!

On another serendipitous note, a few weeks ago I was tracking-down the
source of a quotation (about our work being the invention of 'names'),
and fellow list-members here (or maybe the Python list) were able to
remind me of "The Mental Game of Python" a one-hour talk given by
Raymond Hettinger - one of the "giants" of Python, ie one whose
"shoulders" it is worth "standing upon"
(https://www.youtube.com/watch?v=UANN2Eu6ZnM) Well worth the time - and
maybe you have a YouTube downloader if Internet-reliability is an issue...


Back to the earlier question about IDEs. I'm using PyCharm at the moment
(I use whatever other project-members use/insist I use). PyCharm makes a
point of trying to 'understand' the Python code (which requires a
larger/faster computer than a Notepad-level editor!), and that empowers
functionality such as being able to "refactor" by renaming. Thus, every
use of that name is refactored auto-magically and in one-step (don't
forget to re-run all your pytests afterwards just be sure!). To which
short-cuts, this lazy-boy says, "Oh yeah"!


>> (I'll leave you to research the topics-mentioned that may interest you,
>> as you see fit...)
> 
> I haven't spent anytime on the laptop or the Internet for the fast few
> days and so I haven't had a chance to study the topic of cylomatic
> complexity, however, I do have a Wikipedia page open and I will try to
> gain some understanding of it after I post this e-mail.


Now you have even more...
Isn't life great?
-- 
Regards,
=dn

From alan.gauld at yahoo.co.uk  Tue Nov 30 19:33:22 2021
From: alan.gauld at yahoo.co.uk (Alan Gauld)
Date: Wed, 1 Dec 2021 00:33:22 +0000
Subject: [Tutor] pylint(too-many-nested-blocks)
In-Reply-To: <34dc6d5f-99f7-7826-95f3-1e5965ddfb87@DancesWithMice.info>
References: <2c34791d-dc21-4070-82d2-1c98d67616ce@gmail.com>
 <703ee90c-2d81-5ea3-91aa-7b2a399e4531@DancesWithMice.info>
 <c58dda6d-2da8-8993-787f-77b69314ecf4@gmail.com>
 <34dc6d5f-99f7-7826-95f3-1e5965ddfb87@DancesWithMice.info>
Message-ID: <so6fsj$a9h$1@ciao.gmane.io>

On 30/11/2021 23:19, dn via Tutor wrote:
> If so, there are plenty of "linters" (as others mentioned
> earlier) and other learning-tools. I'm keen on Sourcery (British, hence
> the spelling)

huh?

We spell sorcery like so. (pronounced like horse-ery)
We spell source code like so. (pronounced as s-oh-rce)

I'm not sure where British spelling comes in?

Confused
-- 
Alan G
Author of the Learn to Program web site
http://www.alan-g.me.uk/
http://www.amazon.com/author/alan_gauld
Follow my photo-blog on Flickr at:
http://www.flickr.com/photos/alangauldphotos



From mats at wichmann.us  Tue Nov 30 19:41:17 2021
From: mats at wichmann.us (Mats Wichmann)
Date: Tue, 30 Nov 2021 17:41:17 -0700
Subject: [Tutor] pylint(too-many-nested-blocks)
In-Reply-To: <so6fsj$a9h$1@ciao.gmane.io>
References: <2c34791d-dc21-4070-82d2-1c98d67616ce@gmail.com>
 <703ee90c-2d81-5ea3-91aa-7b2a399e4531@DancesWithMice.info>
 <c58dda6d-2da8-8993-787f-77b69314ecf4@gmail.com>
 <34dc6d5f-99f7-7826-95f3-1e5965ddfb87@DancesWithMice.info>
 <so6fsj$a9h$1@ciao.gmane.io>
Message-ID: <1A5E3038-D275-495D-9AF0-5BFE7760FF83@wichmann.us>

On November 30, 2021 5:33:22 PM MST, Alan Gauld via Tutor <tutor at python.org> wrote:
>On 30/11/2021 23:19, dn via Tutor wrote:
>> If so, there are plenty of "linters" (as others mentioned
>> earlier) and other learning-tools. I'm keen on Sourcery (British, hence
>> the spelling)
>
>huh?
>
>We spell sorcery like so. (pronounced like horse-ery)
>We spell source code like so. (pronounced as s-oh-rce)
>
>I'm not sure where British spelling comes in?
>
>Confused

sourcery is just a kind of pun... and a Pratchett book, if I remember right.
-- 
Sent from a mobile device with K-9 Mail. Please excuse my brevity.

From PyTutor at DancesWithMice.info  Tue Nov 30 20:05:22 2021
From: PyTutor at DancesWithMice.info (dn)
Date: Wed, 1 Dec 2021 14:05:22 +1300
Subject: [Tutor] pylint(too-many-nested-blocks)
In-Reply-To: <so6fsj$a9h$1@ciao.gmane.io>
References: <2c34791d-dc21-4070-82d2-1c98d67616ce@gmail.com>
 <703ee90c-2d81-5ea3-91aa-7b2a399e4531@DancesWithMice.info>
 <c58dda6d-2da8-8993-787f-77b69314ecf4@gmail.com>
 <34dc6d5f-99f7-7826-95f3-1e5965ddfb87@DancesWithMice.info>
 <so6fsj$a9h$1@ciao.gmane.io>
Message-ID: <30b00a08-143e-b3cd-3166-35d34c8f5fa9@DancesWithMice.info>

On 01/12/2021 13.33, Alan Gauld via Tutor wrote:
> On 30/11/2021 23:19, dn via Tutor wrote:
>> If so, there are plenty of "linters" (as others mentioned
>> earlier) and other learning-tools. I'm keen on Sourcery (British, hence
>> the spelling)
> 
> huh?
> 
> We spell sorcery like so. (pronounced like horse-ery)
> We spell source code like so. (pronounced as s-oh-rce)
> 
> I'm not sure where British spelling comes in?
> 
> Confused

That makes two of us!

Blame my trans-Atlantic education (if indeed it achieved anything) in
that I'm often aware of multiple spellings, but too confused to remember
which is which.

Apparently a play-on-words: source and sorcery - just like a Terry
Pratchett book IIRC.

Apologies to all anglophones, and if you wouldn't mind, ever so very,
please pass the HP sauce...
-- 
Regards,
=dn

From alexkleider at gmail.com  Tue Nov 30 20:49:34 2021
From: alexkleider at gmail.com (Alex Kleider)
Date: Tue, 30 Nov 2021 17:49:34 -0800
Subject: [Tutor] pylint(too-many-nested-blocks)
In-Reply-To: <c58dda6d-2da8-8993-787f-77b69314ecf4@gmail.com>
References: <2c34791d-dc21-4070-82d2-1c98d67616ce@gmail.com>
 <703ee90c-2d81-5ea3-91aa-7b2a399e4531@DancesWithMice.info>
 <c58dda6d-2da8-8993-787f-77b69314ecf4@gmail.com>
Message-ID: <CAMCEyD7R-3TjrEMNzkKoTWqvKXy5HsvQWH27K_UJxKfYPEapEw@mail.gmail.com>

This might be of interest (re  cyclomatic complexity) to you.

https://audiolion.github.io/python/2016/10/17/reducing-cyclomatic-complexity.html

On Tue, Nov 30, 2021 at 1:59 PM Phil <phillor9 at gmail.com> wrote:

> Thank you dn for taking the time to write a lengthy informative reply
> and thank you once again Cameron and Mats. I will endeavor to make good
> use of the advice given.
> > Does Python itself see this as an error and stop working, or is it only
> > the code-checker s/w?
>
> It's not so much an error message, rather a recommendation and one that
> I feel that I should act on.
>
> > Were we conducting a Code Review, this function would definitely attract
> > criticism. You have already recognised the complexity, but seem somewhat
> > satisfied - on the  grounds that the whole works.
>
> I think I've only ever produced one application that was truly useful.
> My current project doesn't do anything that others cannot, it's just a
> my-way project and so I could leave it as it is or try to make it look
> more a work of art.
>
>
> > Here's where things become rather subjective. You (no criticism) seem to
> > have a mathematical view of programming,
>
> Isn't computer programming a pursuit based on maths? Even so, I suppose
> the result doesn't need to look like a dog's breakfast.
>
>
> > I have been criticised (but exhibit little remorse) for breaking things
> > down into "smaller" units of code than others feel necessary.
>
> I can see where I could split the function that I posted into two and
> one of those parts could be reused in a yet-to-be-written function. I do
> try to reuse code where I can. I'll need to give a lot more thought to
> how I might reduce the complexity.
>
>
> > Now is a good time pick-up the testing tool's feedback: "understandable
> > and maintainable". It's not merely a matter of
> > "readability"/"understandability", but also maintainability - and that
> > of the objectives of the tool: "testability".
>
> I know that testing tools exist, however, I've always considered their
> use to be beyond the understanding of the neophyte especially this
> amateur programmer.
>
>
> > Earlier the idea of naming a chunk of code was mentioned.
>
> I find it difficult to come up with meaningful names for functions and
> even variables. I know that 'x' or 'y' is often a poor choice and I
> often leave them in place until I can think of something better. Often I
> don't and so they stay, and of course, I forget what they mean the next
> time I look at the code again.
>
>
> > (I'll leave you to research the topics-mentioned that may interest you,
> > as you see fit...)
>
> I haven't spent anytime on the laptop or the Internet for the fast few
> days and so I haven't had a chance to study the topic of cylomatic
> complexity, however, I do have a Wikipedia page open and I will try to
> gain some understanding of it after I post this e-mail.
>
> --
>
> Regards,
> Phil
>
> _______________________________________________
> Tutor maillist  -  Tutor at python.org
> To unsubscribe or change subscription options:
> https://mail.python.org/mailman/listinfo/tutor
>

From cs at cskk.id.au  Tue Nov 30 21:19:22 2021
From: cs at cskk.id.au (Cameron Simpson)
Date: Wed, 1 Dec 2021 13:19:22 +1100
Subject: [Tutor] pylint(too-many-nested-blocks)
In-Reply-To: <c58dda6d-2da8-8993-787f-77b69314ecf4@gmail.com>
References: <c58dda6d-2da8-8993-787f-77b69314ecf4@gmail.com>
Message-ID: <YabbqlyAl9mGdPnG@cskk.homeip.net>

On 01Dec2021 08:57, Phil <phillor9 at gmail.com> wrote:
>>Now is a good time pick-up the testing tool's feedback: 
>>"understandable
>>and maintainable". It's not merely a matter of
>>"readability"/"understandability", but also maintainability - and that
>>of the objectives of the tool: "testability".
>
>I know that testing tools exist, however, I've always considered their 
>use to be beyond the understanding of the neophyte especially this 
>amateur programmer.

Doctest is pretty simple, though it lends itself mostly to pretty simple 
tests. But its so handy for some things that I try to use it as examples 
in the documentation.

Here's an example from my own personal kit. The function's got quite a 
lot of if/else branches and is slightly hard to inspect for correctness.  
But a doctest lets me at least run some simple examples I'm actually 
expecting to use and verify that they get correct output.

That said, here's the function. The docstring is in MarkDown format and 
get written to the module documentation. The doctests are the ">>> " 
prefixed stuff, as in the Python interactive prompt.

    # pylint: disable=redefined-outer-name
    def strip_prefix_n(s, prefix, n=None):
      ''' Strip a leading `prefix` and numeric value `n` from the start of a
          string.  Return the remaining string, or the original string if the
          prefix or numeric value do not match.

          Parameters:
          * `s`: the string to strip
          * `prefix`: the prefix string which must appear at the start of `s`
          * `n`: optional integer value;
            if omitted any value will be accepted, otherwise the numeric
            part must match `n`

          Examples:

             >>> strip_prefix_n('s03e01--', 's', 3)
             'e01--'
             >>> strip_prefix_n('s03e01--', 's', 4)
             's03e01--'
             >>> strip_prefix_n('s03e01--', 's')
             'e01--'
      '''
      s0 = s
      if prefix:
        s = cutprefix(s, prefix)
        if s is s0:
          # no match, return unchanged
          return s0
      else:
        s = s0
      if not s or not s[0].isdigit():
        # no following digits, return unchanged
        return s0
      if n is None:
        # strip all following digits
        s = s.lstrip(digits)
      else:
        # evaluate the numeric part
        s = s.lstrip('0')  # pylint: disable=no-member
        if not s or not s[0].isdigit():
          # all zeroes, leading value is 0
          sn = 0
          pos = 0
        else:
          pos = 1
          slen = len(s)
          while pos < slen and s[pos].isdigit():
            pos += 1
          sn = int(s[:pos])
        if sn != n:
          # wrong numeric value
          return s0
        s = s[pos:]
      return s

So those lines are literally cut/paste from exercises in the interactive 
prompt. To run the tests:

    python3 -m doctest cs/lex.py

which runs all the doctests in the file. "doctest is part of the 
standard library.

This basic level is great for simple assertions which verify basic 
operation of your functions, particularly the cases which mattered to 
you when you wrote them, and various simple corner cases.

There are more elaborate things, and I try to use them, but doctest is a 
great first start, as so easy!

>>Earlier the idea of naming a chunk of code was mentioned.
>
>I find it difficult to come up with meaningful names for functions and 
>even variables. I know that 'x' or 'y' is often a poor choice and I 
>often leave them in place until I can think of something better. Often 
>I don't and so they stay, and of course, I forget what they mean the 
>next time I look at the code again.

Just regular nouns like "word", "vertex" etc are good basics. But don't 
eschew the concise when it matters:

    for i, vertex in vertices:
        print("index", i, "has vertex", vertex)

Nothing wrong with "i" there!

Cheers,
Cameron Simpson <cs at cskk.id.au>