[Tutor] Tutor Digest, Vol 156, Issue 33
Borisco Bizaro
boriscobizaro8 at gmail.com
Tue Feb 14 14:53:54 EST 2017
Please l will like to have a mentor how can I have it
On Feb 14, 2017 09:53, <tutor-request at python.org> wrote:
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> Today's Topics:
>
> 1. Re: Access a .tcl file in python (Alan Gauld)
> 2. Re: Q about .join() Thanks! (David Rock)
> 3. Re: Fwd: Re: GUI for ANSI colors (Alan Gauld)
> 4. Re: Q about .join() Thanks! (Alan Gauld)
> 5. Re: Q about .join() Thanks! (Danny Yoo)
> 6. Re: Q about .join() Thanks! (Peter Otten)
>
>
> ---------- Forwarded message ----------
> From: Alan Gauld <alan.gauld at yahoo.co.uk>
> To: tutor at python.org
> Cc:
> Date: Tue, 14 Feb 2017 01:17:39 +0000
> Subject: Re: [Tutor] Access a .tcl file in python
> On 13/02/17 19:37, Lily ANTONY wrote:
>
> > I have a .tcl file.Does anyone know how to load a .tcl file in to
> python?I
> > need to call the .tcl file in
> > a python program..Thanks!
>
> In general you can't run code for one language in a
> program written in another language. (There are a few
> exceptions, usually where one language is written in
> the other).
>
> The nearest you can usually get is to execute the
> Tcl program using the tcl interpreter (tclsh) from
> the OS using a module like subprocess.
>
> However, Tcl and Python do have a connection via
> the Tkinter module and you can call tcl code
> using Tkinter like so(Python v3):
>
> import tkinter
> tcl = tkinter.Tcl()
> tcl.eval("""
> puts [expr 4+5] # or any other arbitrary tcl
> """)
>
> So to execute a Tcl file you can read the contents
> into a string and then execute that string. Note that
> the return value will always be a string.
>
> 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
>
>
>
>
>
> ---------- Forwarded message ----------
> From: David Rock <david at graniteweb.com>
> To: "tutor at python.org" <tutor at python.org>
> Cc:
> Date: Mon, 13 Feb 2017 19:20:52 -0600
> Subject: Re: [Tutor] Q about .join() Thanks!
>
> > On Feb 13, 2017, at 12:34, SIJIA CHEN <schen557 at wisc.edu> wrote:
> >
> > I find out that the outcome for using .join() on a dictionary is totally
> different than it using on list or string. for example,
> >
> >>>> seq4 = {'hello':1,'good':2,'boy':3,'doiido':4}
> >>>> print ':'.join(seq4)
> > boy:good:doiido:hello
> > So my question is why the outcome doesn't show sequentially as the same
> sequence of the original seq4? What pattern do those "keys" of the
> dictionary in the outcome show ?
>
> Dictionaries (in particular, their keys) are unordered. You can not rely
> on them to be in a particular sequence. The reason for this, from a
> practical perspective, is you are expected to ask for the specific key; you
> should not care about the ordering.
>
> Lists, on the other hand, have a specific order by design so will always
> be in the order they were created.
>
> What are you trying to do with join() on a dictionary in the first place?
> Is there a specific outcome you are trying to get? It’s unlikely that
> using join on a dictionary is what you actually want.
>
> —
> David Rock
> david at graniteweb.com
>
>
>
>
>
>
> ---------- Forwarded message ----------
> From: Alan Gauld <alan.gauld at yahoo.co.uk>
> To: tutor at python.org
> Cc:
> Date: Tue, 14 Feb 2017 01:26:45 +0000
> Subject: Re: [Tutor] Fwd: Re: GUI for ANSI colors
> On 14/02/17 00:58, Alan Gauld forwarded:
>
> > red = '\033[91m'
> > yel = '\033[93m'
> > blu = '\033[34m'
> > grn = '\033[32m'
>
> These are indeed the ANSI codes for the colours but ANSI
> codes only work in an ANSI terminal and GUIs are not
> ANSI terminals. Instead they have their own ideas on
> colours and you need to use those. They all support
> the standard 16 colours used in ANSI however, so in
> your case (for Tkinter at least) just use the names
> 'red', 'yellow', 'blue' and 'green'
>
> > colors = [red, yel, blu, grn]
>
> colors = ['red', 'yellow', 'blue', 'green']
>
>
> > final_word = ''.join(choice(colors) + char for char in word)
>
> But again that won't work in a GUI, you need to use the GUIs
> way of colouring. In Tkinter that's via tags as per my
> previous post, reproduced here).
>
> > ###############################
> > from Tkinter import *
> >
> > n = 0
> > top = Tk()
> > t = Text(top, width=25, height=2)
> > t.pack()
> >
> > # set up tags for the colors
> > colors = ['red','blue','green']
> > for col in colors:
> > t.tag_config(col, foreground=col)
> >
> > def addWords():
> > n = 0
> > for word in "Hello ", "bright ", "world ":
> > t.insert(END,word,colors[n]) #use the color tags
> > n +=1
> >
>
> You need to change the loop to iterate over the letters
> instead of words and choose the tags at random. But that
> should be fairly straightforward.
>
> > Button(top,text="Add words",command=addWords).pack()
> >
> > top.mainloop()
> > ######################
>
>
> --
> 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
>
>
>
>
>
> ---------- Forwarded message ----------
> From: Alan Gauld <alan.gauld at yahoo.co.uk>
> To: tutor at python.org
> Cc:
> Date: Tue, 14 Feb 2017 01:31:57 +0000
> Subject: Re: [Tutor] Q about .join() Thanks!
> On 13/02/17 18:34, SIJIA CHEN wrote:
> > I find out that the outcome for using .join() on a dictionary is
> > totally different than it using on list or string.
>
> Not really, it just looks like that :-)
>
> >
> > >>> seq4 = {'hello':1,'good':2,'boy':3,'doiido':4}
> > >>> print ':'.join(seq4)
> > boy:good:doiido:hello
> > So my question is why the outcome doesn't show sequentially
>
> That's because dictionaries are not stored sequentially and the
> order of retrieval is not guaranteed - it can even change
> during the execution of a program so you should never
> depend on it. That's because dictionaries are optimised
> for random access via the keys not to be iterated over.
>
> You can sort the keys and then pull the values and that will
> give you a guaranteed order but simply printing the dictionary
> (or joining it as you did) is not reliable.
>
> I've a vague memory that recent versions of Python may have
> a special dictionary type that does return items in the order
> they were inserted, but I may be mixing that up with
> another language... Hopefully someone else can provide
> a steer 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
>
>
>
>
>
> ---------- Forwarded message ----------
> From: Danny Yoo <dyoo at hashcollision.org>
> To: Alan Gauld <alan.gauld at yahoo.co.uk>
> Cc: Python Tutor Mailing List <tutor at python.org>
> Date: Mon, 13 Feb 2017 18:10:10 -0800
> Subject: Re: [Tutor] Q about .join() Thanks!
> > That's because dictionaries are not stored sequentially and the
> > order of retrieval is not guaranteed - it can even change
> > during the execution of a program so you should never
> > depend on it. That's because dictionaries are optimised
> > for random access via the keys not to be iterated over.
>
> Moreover, most implementations *deliberately* randomize their iteration
> order to avoid a particular kind of hash collision attack out there in
> the wild. See:
>
> https://en.wikipedia.org/wiki/Collision_attack
>
> https://arstechnica.com/business/2011/12/huge-
> portions-of-web-vulnerable-to-hashing-denial-of-service-attack/
>
> https://mail.python.org/pipermail/python-dev/2011-December/115116.html
>
> for some details.
>
>
> > I've a vague memory that recent versions of Python may have
> > a special dictionary type that does return items in the order
> > they were inserted, but I may be mixing that up with
> > another language... Hopefully someone else can provide
> > a steer there.
>
> In Python, it's collections.OrderedDict:
>
> https://docs.python.org/3.6/library/collections.html#
> collections.OrderedDict
>
> Other languages have similar libraries. Java has LinkedHashMap, for
> example:
>
> https://docs.oracle.com/javase/8/docs/api/java/util/LinkedHashMap.html
>
>
> Best of wishes!
>
>
>
> ---------- Forwarded message ----------
> From: Peter Otten <__peter__ at web.de>
> To: tutor at python.org
> Cc:
> Date: Tue, 14 Feb 2017 09:50:04 +0100
> Subject: Re: [Tutor] Q about .join() Thanks!
> Danny Yoo wrote:
>
> > Moreover, most implementations *deliberately* randomize their iteration
> > order to avoid a particular kind of hash collision attack out there in
> > the wild. See:
>
> In CPython the hash() of a string may change between different runs to fend
> off hash collision attacks, but that does not necessarily change the order
> of iteration:
>
> In Python 3.4 for example both order and hash value change
>
> $ python3.4 -c 'd = dict.fromkeys("foo bar baz".split());
> print(hash("foo"),
> *d)'
> -1599197652882818545 baz bar foo
> $ python3.4 -c 'd = dict.fromkeys("foo bar baz".split());
> print(hash("foo"),
> *d)'
> -7773300350121034240 foo bar baz
> $ python3.4 -c 'd = dict.fromkeys("foo bar baz".split());
> print(hash("foo"),
> *d)'
> 4096077922251392823 baz bar foo
>
> In Python 3.6 on the other side the hash values still change, but
> (insertion) order is preserved:
>
> $ python3.6 -c 'd = dict.fromkeys("foo bar baz".split());
> print(hash("foo"),
> *d)'
> 22453670082131454 foo bar baz
> $ python3.6 -c 'd = dict.fromkeys("foo bar baz".split());
> print(hash("foo"),
> *d)'
> 4601604916521659267 foo bar baz
> $ python3.6 -c 'd = dict.fromkeys("foo bar baz".split());
> print(hash("foo"),
> *d)'
> 5190466601789110813 foo bar baz
>
> So if the OP had used Python 3.6 she would have seen the behaviour she
> expected. However, quoting
> <https://docs.python.org/dev/whatsnew/3.6.html#new-dict-implementation>
>
> """
> The order-preserving aspect of this new [dict] implementation is considered
> an implementation detail and should not be relied upon
> """
>
>
>
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