Path: csiph.com!fu-berlin.de!uni-berlin.de!not-for-mail From: Stephen Hansen Newsgroups: comp.lang.python Subject: Re: Pylint prefers list comprehension over filter... Date: Thu, 05 May 2016 19:57:26 -0700 Lines: 19 Message-ID: References: <572BF2BF.6000000@icloud.com> <1462498631.232041.599637409.25D91C08@webmail.messagingengine.com> <1462503446.248479.599683745.79791DAC@webmail.messagingengine.com> Mime-Version: 1.0 Content-Type: text/plain Content-Transfer-Encoding: 7bit X-Trace: news.uni-berlin.de hTHJTTemCZ4w7f2/iirNQQYMP9ziZAxVFMvx+wraDDeA== Return-Path: X-Original-To: python-list@python.org Delivered-To: python-list@mail.python.org X-Spam-Status: OK 0.001 X-Spam-Evidence: '*H*': 1.00; '*S*': 0.00; 'needed,': 0.05; 'subject:skip:c 10': 0.07; 'oh,': 0.09; 'received:internal': 0.09; 'python': 0.10; '2.7': 0.13; 'output': 0.13; 'thu,': 0.15; '2016': 0.16; 'list*': 0.16; 'message-id:@webmail.messagingengine.com': 0.16; 'received:10.202': 0.16; 'received:10.202.2': 0.16; 'received:66.111': 0.16; 'received:66.111.4': 0.16; 'received:io': 0.16; 'received:messagingengine.com': 0.16; 'received:psf.io': 0.16; 'skips': 0.16; 'wrote:': 0.16; 'string': 0.17; 'stephen': 0.22; '(where': 0.23; 'header:In-Reply-To:1': 0.24; "doesn't": 0.26; 'subject:list': 0.26; 'converting': 0.27; '-0700,': 0.29; 'dan': 0.29; "i'm": 0.30; 'that.': 0.30; 'list': 0.34; 'filter': 0.35; 'returning': 0.35; 'but': 0.36; 'too': 0.36; 'list,': 0.36; 'instead': 0.36; 'to:addr:python-list': 0.36; 'pm,': 0.36; 'subject:: ': 0.37; 'received:10': 0.37; 'difference': 0.38; 'received:66': 0.38; 'building': 0.38; 'means': 0.39; "didn't": 0.39; 'build': 0.40; 'to:addr:python.org': 0.40; 'your': 0.60; 'header:Message-Id:1': 0.61; 'subject:over': 0.84 DKIM-Signature: v=1; a=rsa-sha1; c=relaxed/relaxed; d=ixokai.io; h= content-transfer-encoding:content-type:date:from:in-reply-to :message-id:mime-version:references:subject:to:x-sasl-enc :x-sasl-enc; s=mesmtp; bh=6pGP2yXW7wBaAYG7mrHGm4Yst84=; b=eVFkBG UnkgdIvWifKE7VXuYYD8CttWqMicjAPPchlDXn/p1DvedjMDngD3sq+VYeUwj9mN Poxh6JzIGXgnwJv/jrJ1xfETuPGiseyIBCmCkRhpJf9zU1zdwjHsGG/uXZA7F55i zeUXYjS0l1sHfnvlEdWsEc32C5E8F3JedcuhQ= DKIM-Signature: v=1; a=rsa-sha1; c=relaxed/relaxed; d= messagingengine.com; h=content-transfer-encoding:content-type :date:from:in-reply-to:message-id:mime-version:references :subject:to:x-sasl-enc:x-sasl-enc; s=smtpout; bh=6pGP2yXW7wBaAYG 7mrHGm4Yst84=; b=E1hlKPI+n2DTBXZcG8q4QWteRWGWsWLpvs94iOx0k1N/SDX bZAEXuIFTNPPfhUZ8jFtojude3jIFnVFMuezNSUAyNu85gSR5w6X2QMc4oyL/R5w X+TSuyaII9+TcfIVtdTdjig5dlBcCqcTRb5NKVcYnkJJTuFH7LBxM5TqmMAA= X-Sasl-Enc: P7UmBGVrNDYUJrxtHHOSQTAvF4jmUaGMH3MvcuBB4gSr 1462503446 X-Mailer: MessagingEngine.com Webmail Interface - ajax-140377c4 In-Reply-To: X-BeenThere: python-list@python.org X-Mailman-Version: 2.1.22 Precedence: list List-Id: General discussion list for the Python programming language List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-Mailman-Original-Message-ID: <1462503446.248479.599683745.79791DAC@webmail.messagingengine.com> X-Mailman-Original-References: <572BF2BF.6000000@icloud.com> <1462498631.232041.599637409.25D91C08@webmail.messagingengine.com> Xref: csiph.com comp.lang.python:108213 On Thu, May 5, 2016, at 07:46 PM, Dan Sommers wrote: > On Thu, 05 May 2016 18:37:11 -0700, Stephen Hansen wrote: > > > ''.join(x for x in string if x.isupper()) > > > The difference is, both filter and your list comprehension *build a > > list* which is not needed, and wasteful. The above skips building a > > list, instead returning a generator ... > > filter used to build a list, but now it doesn't (where "used to" means > Python 2.7 and "now" means Python 3.5; I'm too lazy to track down the > exact point(s) at which it changed): Oh, didn't know that. Then again the OP was converting the output of filter *into* a list, which wasted a list either way. -- Stephen Hansen m e @ i x o k a i . i o