Groups | Search | Server Info | Keyboard shortcuts | Login | Register [http] [https] [nntp] [nntps]


Groups > comp.lang.python > #40872

Re: itertools.filterfalse - what is it good for

From Neil Cerutti <neilc@norwich.edu>
Newsgroups comp.lang.python
Subject Re: itertools.filterfalse - what is it good for
Date 2013-03-08 17:02 +0000
Organization Norwich University
Message-ID <apujtvFjj6gU1@mid.individual.net> (permalink)
References <mailman.3087.1362761126.2939.python-list@python.org>

Show all headers | View raw


On 2013-03-08, Wolfgang Maier <wolfgang.maier@biologie.uni-freiburg.de> wrote:
> Dear all,
> can anybody point out a situation where you really need
> itertools.filterfalse() ? So far, I couldn't think of a case
> where you couldn't replace it with a generator expression/if
> combination. e.g.,
>
> a=filterfalse(lambda x: x%2, range(1,101))
> b=(i for i in range(1,101) if not i % 2)
>
> do not return the same object type, but otherwise are achieving
> the same thing. What am I missing here? For sure filterfalse
> exists for a reason?

It must exist for reasons of convenience and efficiency only.

It can trivially be replaced by filter in all cases (at least in
Python 3), but it saves you from a possibly slow extra function
indirection, and also from needing to define one at all.

-- 
Neil Cerutti

Back to comp.lang.python | Previous | NextPrevious in thread | Next in thread | Find similar | Unroll thread


Thread

itertools.filterfalse - what is it good for Wolfgang Maier <wolfgang.maier@biologie.uni-freiburg.de> - 2013-03-08 16:45 +0000
  Re: itertools.filterfalse - what is it good for Neil Cerutti <neilc@norwich.edu> - 2013-03-08 17:02 +0000
  Re: itertools.filterfalse - what is it good for Miki Tebeka <miki.tebeka@gmail.com> - 2013-03-09 12:30 -0800
  Re: itertools.filterfalse - what is it good for Miki Tebeka <miki.tebeka@gmail.com> - 2013-03-09 12:30 -0800

csiph-web