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Groups > comp.lang.python > #47829
| From | Terry Reedy <tjreedy@udel.edu> |
|---|---|
| Subject | Re: Split a list into two parts based on a filter? |
| Date | 2013-06-12 14:47 -0400 |
| References | (3 earlier) <mailman.3023.1370964449.3114.python-list@python.org> <roy-10ED1B.20334411062013@news.panix.com> <CANCy3MzHXNp-m-fKiOr0A+=gvwUgoQS2KaWuWjGgStfk+JQsbQ@mail.gmail.com> <kpa7jo$3um$1@ger.gmane.org> <CAA=1kxR4c+j_iL4-KeFtXB675gX8F982Owu0a-MHGoKQG6wprg@mail.gmail.com> |
| Newsgroups | comp.lang.python |
| Message-ID | <mailman.3118.1371062857.3114.python-list@python.org> (permalink) |
On 6/12/2013 12:57 PM, Fábio Santos wrote:
> Why is there no builtin to consume a generator? I find that odd.
There are several builtins than consume generators -- and do something
useful with the yielded objects. What you mean is "Why is there no
builtin to uselessly consume a generator?" The question almost answers
itself. A generator generates objects to be used.
> On Wed, Jun 12, 2013 at 5:28 PM, Serhiy Storchaka <storchaka@gmail.com> wrote:
>> 12.06.13 09:32, Phil Connell написав(ла):
>>> You could equivalently pass the generator to deque() with maxlen=0 -
>>> this consumes the iterator with constant memory usage.
>> any((new_songs if s.is_new() else old_songs).append(s) for s in songs)
The problem here is that the generator generates and yields an unwanted
sequence of None (references) from the append operations. The proper
loop statement
for s in songs:
(new_songs if s.is_new() else old_songs).append(s)
simply ignores the None return of the appends. Since it does not yield
None over and over, no extra code is needed to ignore what should be
ignored in the first place.
--
Terry Jan Reedy
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Split a list into two parts based on a filter? roy@panix.com (Roy Smith) - 2013-06-10 16:34 -0400
Re: Split a list into two parts based on a filter? Chris Angelico <rosuav@gmail.com> - 2013-06-11 08:50 +1000
Re: Split a list into two parts based on a filter? Roel Schroeven <roel@roelschroeven.net> - 2013-06-11 00:50 +0200
Re: Split a list into two parts based on a filter? Roy Smith <roy@panix.com> - 2013-06-11 00:11 -0400
Re: Split a list into two parts based on a filter? Serhiy Storchaka <storchaka@gmail.com> - 2013-06-11 18:27 +0300
Re: Split a list into two parts based on a filter? Roy Smith <roy@panix.com> - 2013-06-11 20:33 -0400
Re: Split a list into two parts based on a filter? Phil Connell <pconnell@gmail.com> - 2013-06-12 07:32 +0100
Re: Split a list into two parts based on a filter? Roy Smith <roy@panix.com> - 2013-06-12 07:39 -0400
Re: Split a list into two parts based on a filter? Fábio Santos <fabiosantosart@gmail.com> - 2013-06-12 12:51 +0100
Re: Split a list into two parts based on a filter? Jussi Piitulainen <jpiitula@ling.helsinki.fi> - 2013-06-12 15:06 +0300
Re: Split a list into two parts based on a filter? Terry Reedy <tjreedy@udel.edu> - 2013-06-12 14:07 -0400
Re: Split a list into two parts based on a filter? Serhiy Storchaka <storchaka@gmail.com> - 2013-06-12 19:28 +0300
Re: Split a list into two parts based on a filter? Fábio Santos <fabiosantosart@gmail.com> - 2013-06-12 17:57 +0100
Re: Split a list into two parts based on a filter? Terry Reedy <tjreedy@udel.edu> - 2013-06-12 14:47 -0400
Re: Split a list into two parts based on a filter? Oscar Benjamin <oscar.j.benjamin@gmail.com> - 2013-06-13 10:43 +0100
Re: Split a list into two parts based on a filter? Chris Rebert <clp2@rebertia.com> - 2013-06-10 16:03 -0700
Re: Split a list into two parts based on a filter? Tim Chase <python.list@tim.thechases.com> - 2013-06-10 18:10 -0500
Re: Split a list into two parts based on a filter? Fábio Santos <fabiosantosart@gmail.com> - 2013-06-11 00:08 +0100
Re: Split a list into two parts based on a filter? alex23 <wuwei23@gmail.com> - 2013-06-11 17:44 -0700
Re: Split a list into two parts based on a filter? Chris Angelico <rosuav@gmail.com> - 2013-06-11 09:12 +1000
Re: Split a list into two parts based on a filter? Peter Otten <__peter__@web.de> - 2013-06-11 02:11 +0200
Re: Split a list into two parts based on a filter? Peter Otten <__peter__@web.de> - 2013-06-11 08:43 +0200
Re: Split a list into two parts based on a filter? Jonas Geiregat <jonas@geiregat.org> - 2013-06-11 08:47 +0200
Re: Split a list into two parts based on a filter? Fábio Santos <fabiosantosart@gmail.com> - 2013-06-11 14:48 +0100
Re: Split a list into two parts based on a filter? rusi <rustompmody@gmail.com> - 2013-06-11 09:37 -0700
Re: Split a list into two parts based on a filter? Fábio Santos <fabiosantosart@gmail.com> - 2013-06-11 18:05 +0100
Re: Split a list into two parts based on a filter? rusi <rustompmody@gmail.com> - 2013-06-11 10:23 -0700
Re: Split a list into two parts based on a filter? Chris Angelico <rosuav@gmail.com> - 2013-06-12 03:37 +1000
Re: Split a list into two parts based on a filter? rusi <rustompmody@gmail.com> - 2013-06-11 11:13 -0700
Re: Split a list into two parts based on a filter? Fábio Santos <fabiosantosart@gmail.com> - 2013-06-11 19:05 +0100
Re: Split a list into two parts based on a filter? Joshua Landau <joshua.landau.ws@gmail.com> - 2013-06-11 15:22 +0100
Re: Split a list into two parts based on a filter? Serhiy Storchaka <storchaka@gmail.com> - 2013-06-11 18:28 +0300
Re: Split a list into two parts based on a filter? Chris Angelico <rosuav@gmail.com> - 2013-06-12 03:28 +1000
Re: Split a list into two parts based on a filter? Roy Smith <roy@panix.com> - 2013-06-11 20:12 -0400
Re: Split a list into two parts based on a filter? Peter Otten <__peter__@web.de> - 2013-06-11 20:13 +0200
Re: Split a list into two parts based on a filter? Peter Otten <__peter__@web.de> - 2013-06-11 20:18 +0200
Re: Split a list into two parts based on a filter? Chris Angelico <rosuav@gmail.com> - 2013-06-12 04:27 +1000
Re: Split a list into two parts based on a filter? Roel Schroeven <roel@roelschroeven.net> - 2013-06-11 22:22 +0200
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