Path: csiph.com!v102.xanadu-bbs.net!xanadu-bbs.net!goblin1!goblin2!goblin.stu.neva.ru!newsfeed.xs4all.nl!newsfeed2.news.xs4all.nl!xs4all!post.news.xs4all.nl!not-for-mail Return-Path: X-Original-To: python-list@python.org Delivered-To: python-list@mail.python.org X-Spam-Status: OK 0.002 X-Spam-Evidence: '*H*': 1.00; '*S*': 0.00; 'explicit': 0.07; 'subject:two': 0.07; '[1,': 0.09; '[],': 0.09; 'naturally': 0.09; 'snippet': 0.09; 'subject:into': 0.09; 'thrown': 0.09; 'cc:addr :python-list': 0.11; '>>': 0.16; '(read': 0.16; 'above)': 0.16; 'expressions,': 0.16; 'pythonic': 0.16; 'readability': 0.16; 'spurious': 0.16; 'subject:based': 0.16; 'to:addr:web.de': 0.16; 'all.': 0.16; 'wrote:': 0.18; 'version.': 0.19; 'written': 0.21; '>>>': 0.22; 'cc:addr:python.org': 0.22; '>>>': 0.24; 'cc:2**0': 0.24; 'cc:no real name:2**0': 0.24; "i've": 0.25; '>': 0.26; 'header:In-Reply-To:1': 0.27; 'statement': 0.30; 'subject:list': 0.30; 'message-id:@mail.gmail.com': 0.30; "i'm": 0.30; 'code': 0.31; 'implicit': 0.31; "i'd": 0.34; 'could': 0.34; 'agree': 0.35; 'something': 0.35; 'but': 0.35; 'received:google.com': 0.35; 'subject:?': 0.36; 'should': 0.36; 'turn': 0.37; 'list': 0.37; 'skip:o 20': 0.38; 'skip:& 10': 0.38; 'rather': 0.38; 'expect': 0.39; 'does': 0.39; 'sure': 0.39; 'even': 0.60; 'within': 0.65; 'side': 0.67; 'hour': 0.70; 'increase': 0.74; 'confusion.': 0.84; 'odds': 0.84; '2013': 0.98 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20120113; h=mime-version:in-reply-to:references:date:message-id:subject:from:to :cc:content-type; bh=cROGXQIKgLvQhLH1ztxhKRfsiEOrfJ0wWVmjDQxpxRs=; b=NewZLYtKS9NkDrxfM39I7VdAmtgJv2YeUu/4ydJRNvKjHy9E4T+KIjMXbW4SG8+Zm+ Lt4njcbBBgFf6ISrxcCHbVEN8HWhZJ76ozHrlwpjZUkWTNrve35ZCd6gzjVMPMIi8gQH Z9chtd8h2Hx2e+l20mgAGk3wF8EsDhgu1TATPsc1M9CR/QQlaaqQi/7/Hgh4p9xBw8E3 Kq2OlLhyfS9LZCou3G0/PqDucq+wDKCiBf+OVHJ7K6msC0s1XzSlxbXJgLWBGPOjUMPa cC+oukilsB792Sfaxl4Xh72BVsFM7TPmyITfWsoIPzejlt4EfRYud4aSnGKZi5zmjL7H p81Q== MIME-Version: 1.0 X-Received: by 10.224.105.199 with SMTP id u7mr16050930qao.33.1370958500671; Tue, 11 Jun 2013 06:48:20 -0700 (PDT) In-Reply-To: References: Date: Tue, 11 Jun 2013 14:48:20 +0100 Subject: Re: Split a list into two parts based on a filter? From: =?ISO-8859-1?Q?F=E1bio_Santos?= To: Peter Otten <__peter__@web.de> Content-Type: multipart/alternative; boundary=20cf306844d56f363d04dee126e5 Cc: python-list@python.org X-BeenThere: python-list@python.org X-Mailman-Version: 2.1.15 Precedence: list List-Id: General discussion list for the Python programming language List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Newsgroups: comp.lang.python Message-ID: Lines: 112 NNTP-Posting-Host: 2001:888:2000:d::a6 X-Trace: 1370958503 news.xs4all.nl 15872 [2001:888:2000:d::a6]:58767 X-Complaints-To: abuse@xs4all.nl Xref: csiph.com comp.lang.python:47661 --20cf306844d56f363d04dee126e5 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: quoted-printable On 11 Jun 2013 07:47, "Peter Otten" <__peter__@web.de> wrote: > > F=E1bio Santos wrote: > > > On 10 Jun 2013 23:54, "Roel Schroeven" wrote: > >> > >> You could do something like: > >> > >> new_songs, old_songs =3D [], [] > >> [(new_songs if s.is_new() else old_songs).append(s) for s in songs] > >> > >> But I'm not sure that that's any better than the long version. > > > > This is so beautiful! > > It makes me cringe. > > This code does spurious work to turn what is naturally written as a for loop > into a list comprehension that is thrown away immediately. I think I'd even > prefer this "gem" > > >>> evens =3D [] > >>> odds =3D [item for item in range(10) if item % 2 or evens.append(item= )] > >>> evens, odds > ([0, 2, 4, 6, 8], [1, 3, 5, 7, 9]) > > but if I have my way every side effect in a list comprehension should be > punished with an extra hour of bug-hunting ;) > What I like so much about it is the .. if .. else .. Within the parenthesis and the append() call outside these parenthesis. I agree it would be best written as a for loop, to increase readability and avoid confusion. I always expect list comprehensions to be used as expressions, and its use as a (single-expression) statement is rather odd. On 11 Jun 2013 07:52, "Jonas Geiregat" wrote: > I must disagree , this is unreadable and in my honor opinion not Pythonic at all. > I've learned it's always better to be explicit then implicit, and this snippet of code does a lot in an implicit way. > (Read above) --20cf306844d56f363d04dee126e5 Content-Type: text/html; charset=ISO-8859-1 Content-Transfer-Encoding: quoted-printable


On 11 Jun 2013 07:47, "Peter Otten" <__peter__@web.de> wrote:
>
> F=E1bio Santos wrote:
>
> > On 10 Jun 2013 23:54, "Roel Schroeven" <roel@roelschroeven.net> wrote:
> >>
> >> You could do something like:
> >>
> >> new_songs, old_songs =3D [], []
> >> [(new_songs if s.is_new() else old_songs).append(s) for s in = songs]
> >>
> >> But I'm not sure that that's any better than the long= version.
> >
> > This is so beautiful!
>
> It makes me cringe.
>
> This code does spurious work to turn what is naturally written as a fo= r loop
> into a list comprehension that is thrown away immediately. I think I&#= 39;d even
> prefer this "gem"
>
> >>> evens =3D []
> >>> odds =3D [item for item in range(10) if item % 2 or evens= .append(item)]
> >>> evens, odds
> ([0, 2, 4, 6, 8], [1, 3, 5, 7, 9])
>
> but if I have my way every side effect in a list comprehension should = be
> punished with an extra hour of bug-hunting ;)
>

What I like so much about it is the .. if .. else .. Within = the parenthesis and the append() call outside these parenthesis.

I agree it would be best written as a for loop, to increase = readability and avoid confusion. I always expect list comprehensions to be = used as expressions, and its use as a (single-expression) statement is rath= er odd.

On 11 Jun 2013 07:52, "Jonas Geiregat" <jonas@geiregat.org> wrote:
> I must disagree , this is unreadable and in my honor opinion not Pytho= nic at all.
> I've learned it's always better to be explicit then implicit, = and this snippet of code does a lot in an implicit way.
>

(Read above)

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