Path: csiph.com!v102.xanadu-bbs.net!xanadu-bbs.net!goblin1!goblin2!goblin.stu.neva.ru!newsfeed.xs4all.nl!newsfeed1.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 0.158 X-Spam-Level: * X-Spam-Evidence: '*H*': 0.69; '*S*': 0.00; 'subject:question': 0.10; 'cc:addr:python-list': 0.11; '24,': 0.16; 'index': 0.16; 'wrote:': 0.18; 'email addr:gmail.com>': 0.22; 'cc:addr:python.org': 0.22; 'cc:2**0': 0.24; 'cc:no real name:2**0': 0.24; '>': 0.26; 'header:In-Reply-To:1': 0.27; 'message-id:@mail.gmail.com': 0.30; "i'm": 0.30; 'produces': 0.31; 'provided,': 0.31; 'fri,': 0.33; 'received:209.85': 0.35; 'but': 0.35; 'received:google.com': 0.35; 'library.': 0.36; 'sequence': 0.36; 'subject:Simple': 0.36; 'should': 0.36; 'list': 0.37; 'received:209': 0.37; 'easiest': 0.38; 'pm,': 0.38; 'most': 0.60; 'tell': 0.60; 'more': 0.64; 'different': 0.65; 'taking': 0.65; 'to:addr:gmail.com': 0.65; 'obvious': 0.74; 'idiot': 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=nnF79MDWBeC62YsMvD4rd/BJo1MfSVpPOzkfR6UUXtc=; b=sddVTWe3MZtd9JK2X0OydtxXE+HC5mP+iR1gER3XFb4jkFUjB+HUL9gIAB3vcgA6zx zQz1OLJX7UPVZ4kOaV3PGttNBzRHGzIYPeotgidtuEcjfrkeG6B4HOPv/lQ1JSdSuwyp RUpO81b40wjBfqP8yMmOvjfDkqBfJFdt+Z0zAyzowdPsAVQwVnIH/VXdP4yHBHQVAFo1 qEOvpMIamHh+2uKMkCNGrS+Fd7ROY8ZuJok57VcImrL3kfKJy3jzSLQunn00Ng/GnSLY 4E4m+GUqZIQ4lj8qlDDKqUhZ2bvD3Byckwjkq15ib+X6sCaWXMJ+JUd+OSv83J14LIJl Yf5Q== MIME-Version: 1.0 X-Received: by 10.229.175.137 with SMTP id ba9mr1498923qcb.43.1369385228030; Fri, 24 May 2013 01:47:08 -0700 (PDT) In-Reply-To: References: Date: Fri, 24 May 2013 09:47:07 +0100 Subject: Re: Simple algorithm question - how to reorder a sequence economically From: =?ISO-8859-1?Q?F=E1bio_Santos?= To: Chris Angelico Content-Type: multipart/alternative; boundary=001a11c2dec413f89c04dd72d831 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: 46 NNTP-Posting-Host: 2001:888:2000:d::a6 X-Trace: 1369385236 news.xs4all.nl 15938 [2001:888:2000:d::a6]:54008 X-Complaints-To: abuse@xs4all.nl Xref: csiph.com comp.lang.python:45872 --001a11c2dec413f89c04dd72d831 Content-Type: text/plain; charset=ISO-8859-1 On 24 May 2013 09:41, "Chris Angelico" wrote: > > On Fri, May 24, 2013 at 6:14 PM, Peter Brooks > wrote: > > What is the easiest way to reorder a sequence pseudo-randomly? > > > > That is, for a sequence 1,2,3,4 to produce an arbitrary ordering (eg > > 2,1,4,3) that is different each time. > > ... > It works, it produces a unique list for any given index provided, but > it's not the cleanest or most efficient. But I know someone'll improve > on it... or tell me I'm an idiot for not taking a more obvious > approach :) > > ChrisA I think that is pretty much itertools.permutations from the standard library. The OP should check it out. --001a11c2dec413f89c04dd72d831 Content-Type: text/html; charset=ISO-8859-1


On 24 May 2013 09:41, "Chris Angelico" <rosuav@gmail.com> wrote:
>
> On Fri, May 24, 2013 at 6:14 PM, Peter Brooks
> <peter.h.m.brooks@gmail.com> wrote:
> > What is the easiest way to reorder a sequence pseudo-randomly?
> >
> > That is, for a sequence 1,2,3,4 to produce an arbitrary ordering (eg
> > 2,1,4,3) that is different each time.
> >
...
> It works, it produces a unique list for any given index provided, but
> it's not the cleanest or most efficient. But I know someone'll improve
> on it... or tell me I'm an idiot for not taking a more obvious
> approach :)
>
> ChrisA

I think that is pretty much itertools.permutations from the standard library. The OP should check it out.

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