Path: csiph.com!x330-a1.tempe.blueboxinc.net!usenet.pasdenom.info!gegeweb.org!de-l.enfer-du-nord.net!feeder2.enfer-du-nord.net!tudelft.nl!txtfeed1.tudelft.nl!multikabel.net!newsfeed10.multikabel.net!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 0.009
X-Spam-Evidence: '*H*': 0.98; '*S*': 0.00; '"""': 0.07; '__name__': 0.09; 'lawrence': 0.09; 'received:80.91': 0.09; 'received:80.91.229': 0.09; 'received:gmane.org': 0.09; 'received:list': 0.09; 'def': 0.13; '"__main__":': 0.16; 'better?': 0.16; 'doctest': 0.16; 'sequence,': 0.16; 'wrote:': 0.18; '>>>': 0.18; 'header:In-Reply-To:1': 0.22; 'indices': 0.23; 'index': 0.24; "python's": 0.24; 'stuff': 0.26; 'import': 0.27; "i'm": 0.28; 'yield': 0.29; 'definition': 0.30; 'header:User- Agent:1': 0.33; 'instead': 0.33; 'header:X-Complaints-To:1': 0.34; 'from:addr:yahoo.co.uk': 0.34; 'running': 0.34; 'to:addr:python- list': 0.35; 'starting': 0.36; 'beginning': 0.36; 'received:org': 0.36; 'sequence': 0.37; 'but': 0.37; 'skip:" 10': 0.37; 'could': 0.38; 'some': 0.38; 'i.e.': 0.39; 'received:78': 0.40; 'to:addr:python.org': 0.40; 'back': 0.60; 'kinds': 0.64; 'designed': 0.69; 'winner': 0.76; 'cycling': 0.84; 'received:as13285.net': 0.84
X-Injected-Via-Gmane: http://gmane.org/
To: python-list@python.org
From: Mark Lawrence <breamoreboy@yahoo.co.uk>
Subject: Re: Cycle around a sequence
Date: Wed, 08 Feb 2012 22:47:04 +0000
References: <mailman.5525.1328663401.27778.python-list@python.org> <9pfeutFtjiU2@mid.individual.net>
Mime-Version: 1.0
Content-Type: text/plain; charset=ISO-8859-1; format=flowed
Content-Transfer-Encoding: 7bit
X-Gmane-NNTP-Posting-Host: host-78-147-179-19.as13285.net
User-Agent: Mozilla/5.0 (Windows NT 6.0; rv:10.0) Gecko/20120129 Thunderbird/10.0
In-Reply-To: <9pfeutFtjiU2@mid.individual.net>
X-Antivirus: avast! (VPS 120208-0, 08/02/2012), Outbound message
X-Antivirus-Status: Clean
X-BeenThere: python-list@python.org
X-Mailman-Version: 2.1.12
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.5554.1328741236.27778.python-list@python.org>
Lines: 37
NNTP-Posting-Host: 2001:888:2000:d::a6
X-Trace: 1328741236 news.xs4all.nl 6906 [2001:888:2000:d::a6]:36899
X-Complaints-To: abuse@xs4all.nl
Xref: x330-a1.tempe.blueboxinc.net comp.lang.python:20036

On 08/02/2012 14:25, Neil Cerutti wrote:
> On 2012-02-08, Mark Lawrence<breamoreboy@yahoo.co.uk>  wrote:
>> I'm looking at a way of cycling around a sequence i.e. starting
>> at some given location in the middle of a sequence and running
>> to the end before coming back to the beginning and running to
>> the start place.  About the best I could come up with is the
>> following, any better ideas for some definition of better?
>
> Python's indices were designed for these kinds of shenanigans.
>
> def rotated(seq, n):
>      """Iterate through all of seq, but starting from index n.
>
>      >>>  ", ".join(str(n) for n in rotated(range(5), 3))
>      '3, 4, 0, 1, 2'
>      """
>
>      i = n - len(seq)
>      while i<  n:
>          yield seq[i]
>          i += 1
>
> if __name__ == "__main__":
>      import doctest
>      doctest.testmod()
>
> If you have merely an iterable instead of a sequence, then look
> to some of the other clever stuff already posted.
>

The winner :)

-- 
Cheers.

Mark Lawrence.