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

Groups > comp.lang.python > #35790

Re: dict comprehension question.

Path csiph.com!newsfeed.hal-mli.net!feeder3.hal-mli.net!newsfeed.hal-mli.net!feeder1.hal-mli.net!newsreader4.netcologne.de!news.netcologne.de!xlned.com!feeder7.xlned.com!news2.euro.net!newsgate.cistron.nl!newsgate.news.xs4all.nl!post.news.xs4all.nl!not-for-mail
Return-Path <python-python-list@m.gmane.org>
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; 'skip:[ 20': 0.03; 'subject:skip:c 10': 0.07; 'indeed,': 0.09; 'received:80.91': 0.09; 'received:80.91.229': 0.09; 'received:gmane.org': 0.09; 'received:list': 0.09; 'terry': 0.09; 'distinct': 0.16; 'it..': 0.16; 'received:80.91.229.3': 0.16; 'received:plane.gmane.org': 0.16; 'reedy': 0.16; 'subject:question.': 0.16; 'wrote:': 0.17; 'items.': 0.17; 'jan': 0.18; '>>>': 0.18; 'header:In-Reply-To:1': 0.25; 'header:User-Agent:1': 0.26; 'header:X-Complaints-To:1': 0.28; 'turns': 0.33; 'problem': 0.33; 'to:addr:python-list': 0.33; 'problem,': 0.35; 'pm,': 0.35; 'received:org': 0.36; 'skip:{ 10': 0.36; "didn't": 0.36; 'subject:: ': 0.38; 'to:addr:python.org': 0.39; 'where': 0.40; 'header:Received:5': 0.40; 'think': 0.40; 'received:fios.verizon.net': 0.84; 'joel': 0.91
X-Injected-Via-Gmane http://gmane.org/
To python-list@python.org
From Terry Reedy <tjreedy@udel.edu>
Subject Re: dict comprehension question.
Date Sat, 29 Dec 2012 18:22:20 -0500
References <724d4fea-606a-4503-b538-87442f6bcebc@ci3g2000vbb.googlegroups.com> <50DF4C00.2020505@lightbird.net> <50DF4E15.1030700@lightbird.net> <CAPM-O+w8aYZ2zJcmc+ZyHOHmA7yt8OYPYAqhGWSB5tQgbnqRdA@mail.gmail.com> <50DF6334.7050600@lightbird.net>
Mime-Version 1.0
Content-Type text/plain; charset=UTF-8; format=flowed
Content-Transfer-Encoding 7bit
X-Gmane-NNTP-Posting-Host pool-173-75-251-66.phlapa.fios.verizon.net
User-Agent Mozilla/5.0 (Windows NT 6.1; WOW64; rv:17.0) Gecko/17.0 Thunderbird/17.0
In-Reply-To <50DF6334.7050600@lightbird.net>
X-BeenThere python-list@python.org
X-Mailman-Version 2.1.15
Precedence list
List-Id General discussion list for the Python programming language <python-list.python.org>
List-Unsubscribe <http://mail.python.org/mailman/options/python-list>, <mailto:python-list-request@python.org?subject=unsubscribe>
List-Archive <http://mail.python.org/pipermail/python-list/>
List-Post <mailto:python-list@python.org>
List-Help <mailto:python-list-request@python.org?subject=help>
List-Subscribe <http://mail.python.org/mailman/listinfo/python-list>, <mailto:python-list-request@python.org?subject=subscribe>
Newsgroups comp.lang.python
Message-ID <mailman.1453.1356823379.29569.python-list@python.org> (permalink)
Lines 22
NNTP-Posting-Host 2001:888:2000:d::a6
X-Trace 1356823379 news.xs4all.nl 6908 [2001:888:2000:d::a6]:50771
X-Complaints-To abuse@xs4all.nl
Xref csiph.com comp.lang.python:35790

Show key headers only | View raw

On 12/29/2012 4:40 PM, Mitya Sirenef wrote:
> On 12/29/2012 03:15 PM, Joel Goldstick wrote:

>> Would this help:
>>
>>      >>> w = [1,2,3,1,2,4,4,5,6,1]
>>      >>> s = set(w)
>>      >>> s
>>      set([1, 2, 3, 4, 5, 6])
>>      >>> {x:w.count(x) for x in s}
>>      {1: 3, 2: 2, 3: 1, 4: 2, 5: 1, 6: 1}
>> >>>
>
>
> Indeed, this is much better -- I didn't think of it..

It still turns an O(n) problem into an O(k*n) problem, where k is the 
number of distinct items.

-- 
Terry Jan Reedy

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

Thread

dict comprehension question. Quint Rankid <qbr567@gmail.com> - 2012-12-29 11:48 -0800
  Re: dict comprehension question. Roy Smith <roy@panix.com> - 2012-12-29 14:58 -0500
  Re: dict comprehension question. Mitya Sirenef <msirenef@lightbird.net> - 2012-12-29 15:01 -0500
  Re: dict comprehension question. Mitya Sirenef <msirenef@lightbird.net> - 2012-12-29 15:09 -0500
  Re: dict comprehension question. Joel Goldstick <joel.goldstick@gmail.com> - 2012-12-29 15:15 -0500
  Re: dict comprehension question. Peter Otten <__peter__@web.de> - 2012-12-29 21:32 +0100
  Re: dict comprehension question. MRAB <python@mrabarnett.plus.com> - 2012-12-29 20:39 +0000
  Re: dict comprehension question. Mitya Sirenef <msirenef@lightbird.net> - 2012-12-29 16:40 -0500
  Re: dict comprehension question. Terry Reedy <tjreedy@udel.edu> - 2012-12-29 18:22 -0500
  Re: dict comprehension question. Terry Reedy <tjreedy@udel.edu> - 2012-12-29 18:56 -0500
    Re: dict comprehension question. Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2013-01-01 03:10 +0000
      Re: dict comprehension question. 88888 Dihedral <dihedral88888@googlemail.com> - 2013-01-01 00:40 -0800
  Re: dict comprehension question. Tim Chase <python.list@tim.thechases.com> - 2012-12-29 18:26 -0600
  Re: dict comprehension question. Joel Goldstick <joel.goldstick@gmail.com> - 2012-12-29 23:10 -0500

csiph-web