Hello All, pluck() is a beautiful function which is in underscore.js library. Described as "A convenient version of what is perhaps the most common use-case for map: extracting a list of property values." http://documentcloud.github.com/underscore/#pluck What about it implementing for python lists? And maybe for other iterables?
On Sat, Jun 02, 2012 at 12:10:03AM +0300, Cenk Alt?? <cenkalti@gmail.com> wrote:
Like operator.attrgetter? http://docs.python.org/library/operator.html#operator.attrgetter Oleg. -- Oleg Broytman http://phdru.name/ phd@phdru.name Programmers don't die, they just GOSUB without RETURN.
I must confess that I don't find "pluck" a very intuitive name for this functionality. For me it was evocative of what pop currently does. That's an N of 1 so maybe I'm just wrong on that one. More importantly, this would make the use of a list method dependent upon the type of the contained items. (works for dicts and nothing else) That would be unprecedented for list methods and potentially confusing. What would be the behavior if the list contains non-dicts? On Fri, Jun 1, 2012 at 2:48 PM, Cenk Altı <cenkalti@gmail.com> wrote:
If the item has definded a method "__getitem__" it will be called, else "__getattribute__" is called. I know list comprehensions are same thing but .pluck seems easier to read and write I think (no need to write a temporary variable in list comprehension, and also square brackets). Just an idea... On Sat, Jun 2, 2012 at 1:53 AM, Alexandre Zani <alexandre.zani@gmail.com> wrote:
On 2 juin 2012, at 07:25, Cenk Altı <cenkalti@gmail.com> wrote:
If the item has definded a method "__getitem__" it will be called, else "__getattribute__" is called.
That is complète insanity and goes against pretty much all existing python code. Some types make keys available as both items and attributes but I do not know of any operation which does so.
Not a useful one, if you dislike the iteration variable of comprehensions you may use 'map' with itemgetter or attrgetter. Not to mention they are more flexible than pluck (they can extract multiple items or attributes, and attrgetter supports "deep" dotted paths)
On Sat, 2 Jun 2012 00:48:04 +0300 Cenk Altı <cenkalti@gmail.com> wrote:
l.pluck('name') is more readable IMO.
Only because you already associate "pluck" with that meaning. As others said, "pluck" to me implies something like "pop". The list comprehension spelling doesn't suffer from this problem, and provides a lot more flexibility. If you don't like list comprehensions, use map and the operator module. Even if it is more readable, it's more semantic load. It's another container operator (and one that's only useful in the special case of a list of maps) people have to learn. Since it saves 0 lines of code over either of existing mechanisms, the extra load comes for no advantage. -1 <mike -- Mike Meyer <mwm@mired.org> http://www.mired.org/ Independent Software developer/SCM consultant, email for more information. O< ascii ribbon campaign - stop html mail - www.asciiribbon.org
On Fri, Jun 1, 2012 at 5:48 PM, Cenk Altı <cenkalti@gmail.com> wrote:
l.pluck('name') is more readable IMO.
That's not how the library you linked to works, as far as I can tell. Based on the sample usage at http://documentcloud.github.com/underscore/#pluck, pluck is a function taking an iterable of dictionaries and the key, so I think the python equivalent is: def pluck(iterable, key): return [item[key] for item in iterable] stooges = [{'name' : 'moe', 'age' : 40}, {'name' : 'larry', 'age' : 50}, {'name' : 'curly', 'age' : 60}] print (pluck(stooges, 'name'))
['moe', 'larry', 'curly']
-- Jerry
There are already at least two easy ways to do this:
Also I'm used to such functions being called "collect" (Ruby) or "map" (Python, jQuery) and accepting a function/block as an argument. In Ruby-on-Rails it can be &:name as a shorthand for {|item| item[:name]}, which is equivalent to itemgetter('name') in Python. So if you insist of making it shorter (but less readable) you could do:
On 06/01/2012 11:10 PM, Cenk Altı wrote:
Forgive the out of context drive-by comments... On Sat, Jun 2, 2012 at 8:54 AM, Mathias Panzenböck <grosser.meister.morti@gmx.net> wrote:
Bingo. Doesn't need improvements.
If I saw this I would have to think a lot harder before I figured what it meant. (Especially without the output example.) Let's remember KISS. -- --Guido van Rossum (python.org/~guido)
On 06/02/2012 08:50 PM, Westley Martínez wrote:
Yes, yes. I opened a Python 2 shell to write the example code. Python 2 is still the default in most (all?) Linux distributions. To get a list from that just wrap list() around it. I consider this behaviour (that map returns a generator) in fact superior to what's available in other languages. You can then pass that to whatever constructor you like (e.g. set() or tuple()) or take only some of the values and then stop without calculating (and allocating) it all. -panzi
On Fri, Jun 1, 2012 at 5:10 PM, Cenk Altı <cenkalti@gmail.com> wrote:
This is a case where a simple list comprehension or generator expression would be a lot easier to understand than remembering what a rarely used method name does. Also, it couples two distinct interfaces, iterables and mappings, in a way that is generally frowned upon in Python.
-- Read my blog! I depend on your acceptance of my opinion! I am interesting! http://techblog.ironfroggy.com/ Follow me if you're into that sort of thing: http://www.twitter.com/ironfroggy
On Sat, Jun 02, 2012 at 12:10:03AM +0300, Cenk Alt?? <cenkalti@gmail.com> wrote:
Like operator.attrgetter? http://docs.python.org/library/operator.html#operator.attrgetter Oleg. -- Oleg Broytman http://phdru.name/ phd@phdru.name Programmers don't die, they just GOSUB without RETURN.
I must confess that I don't find "pluck" a very intuitive name for this functionality. For me it was evocative of what pop currently does. That's an N of 1 so maybe I'm just wrong on that one. More importantly, this would make the use of a list method dependent upon the type of the contained items. (works for dicts and nothing else) That would be unprecedented for list methods and potentially confusing. What would be the behavior if the list contains non-dicts? On Fri, Jun 1, 2012 at 2:48 PM, Cenk Altı <cenkalti@gmail.com> wrote:
If the item has definded a method "__getitem__" it will be called, else "__getattribute__" is called. I know list comprehensions are same thing but .pluck seems easier to read and write I think (no need to write a temporary variable in list comprehension, and also square brackets). Just an idea... On Sat, Jun 2, 2012 at 1:53 AM, Alexandre Zani <alexandre.zani@gmail.com> wrote:
On 2 juin 2012, at 07:25, Cenk Altı <cenkalti@gmail.com> wrote:
If the item has definded a method "__getitem__" it will be called, else "__getattribute__" is called.
That is complète insanity and goes against pretty much all existing python code. Some types make keys available as both items and attributes but I do not know of any operation which does so.
Not a useful one, if you dislike the iteration variable of comprehensions you may use 'map' with itemgetter or attrgetter. Not to mention they are more flexible than pluck (they can extract multiple items or attributes, and attrgetter supports "deep" dotted paths)
On Sat, 2 Jun 2012 00:48:04 +0300 Cenk Altı <cenkalti@gmail.com> wrote:
l.pluck('name') is more readable IMO.
Only because you already associate "pluck" with that meaning. As others said, "pluck" to me implies something like "pop". The list comprehension spelling doesn't suffer from this problem, and provides a lot more flexibility. If you don't like list comprehensions, use map and the operator module. Even if it is more readable, it's more semantic load. It's another container operator (and one that's only useful in the special case of a list of maps) people have to learn. Since it saves 0 lines of code over either of existing mechanisms, the extra load comes for no advantage. -1 <mike -- Mike Meyer <mwm@mired.org> http://www.mired.org/ Independent Software developer/SCM consultant, email for more information. O< ascii ribbon campaign - stop html mail - www.asciiribbon.org
On Fri, Jun 1, 2012 at 5:48 PM, Cenk Altı <cenkalti@gmail.com> wrote:
l.pluck('name') is more readable IMO.
That's not how the library you linked to works, as far as I can tell. Based on the sample usage at http://documentcloud.github.com/underscore/#pluck, pluck is a function taking an iterable of dictionaries and the key, so I think the python equivalent is: def pluck(iterable, key): return [item[key] for item in iterable] stooges = [{'name' : 'moe', 'age' : 40}, {'name' : 'larry', 'age' : 50}, {'name' : 'curly', 'age' : 60}] print (pluck(stooges, 'name'))
['moe', 'larry', 'curly']
-- Jerry
There are already at least two easy ways to do this:
Also I'm used to such functions being called "collect" (Ruby) or "map" (Python, jQuery) and accepting a function/block as an argument. In Ruby-on-Rails it can be &:name as a shorthand for {|item| item[:name]}, which is equivalent to itemgetter('name') in Python. So if you insist of making it shorter (but less readable) you could do:
On 06/01/2012 11:10 PM, Cenk Altı wrote:
Forgive the out of context drive-by comments... On Sat, Jun 2, 2012 at 8:54 AM, Mathias Panzenböck <grosser.meister.morti@gmx.net> wrote:
Bingo. Doesn't need improvements.
If I saw this I would have to think a lot harder before I figured what it meant. (Especially without the output example.) Let's remember KISS. -- --Guido van Rossum (python.org/~guido)
On 06/02/2012 08:50 PM, Westley Martínez wrote:
Yes, yes. I opened a Python 2 shell to write the example code. Python 2 is still the default in most (all?) Linux distributions. To get a list from that just wrap list() around it. I consider this behaviour (that map returns a generator) in fact superior to what's available in other languages. You can then pass that to whatever constructor you like (e.g. set() or tuple()) or take only some of the values and then stop without calculating (and allocating) it all. -panzi
On Fri, Jun 1, 2012 at 5:10 PM, Cenk Altı <cenkalti@gmail.com> wrote:
This is a case where a simple list comprehension or generator expression would be a lot easier to understand than remembering what a rarely used method name does. Also, it couples two distinct interfaces, iterables and mappings, in a way that is generally frowned upon in Python.
-- Read my blog! I depend on your acceptance of my opinion! I am interesting! http://techblog.ironfroggy.com/ Follow me if you're into that sort of thing: http://www.twitter.com/ironfroggy
participants (12)
-
Alexandre Zani -
Calvin Spealman -
Cenk Altı -
Guido van Rossum -
Jerry Hill -
Masklinn -
Mathias Panzenböck -
Mike Graham -
Mike Meyer -
Oleg Broytman -
Serhiy Storchaka -
Westley Martínez