Path: csiph.com!v102.xanadu-bbs.net!xanadu-bbs.net!us.feeder.erje.net!feeder.erje.net!eu.feeder.erje.net!newsfeed.freenet.ag!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 0.003
X-Spam-Evidence: '*H*': 0.99; '*S*': 0.00; 'received:80.91': 0.09; 'received:80.91.229': 0.09; 'received:gmane.org': 0.09; 'received:list': 0.09; '2],': 0.16; '3],': 0.16; '[2,': 0.16; 'numpy': 0.16; 'received:80.91.229.3': 0.16; 'received:dip.t-dialin.net': 0.16; 'received:plane.gmane.org': 0.16; 'received:t-dialin.net': 0.16; 'subject:array': 0.16; 'wrote:': 0.17; '>>>': 0.18; 'header:User-Agent:1': 0.26; 'header:X-Complaints-To:1': 0.28; 'to:addr:python-list': 0.33; 'there': 0.35; 'received:org': 0.36; 'does': 0.37; 'subject:: ': 0.38; 'mean': 0.38; 'to:addr:python.org': 0.39; 'header:Received:5': 0.40; 'skip:a 30': 0.60
X-Injected-Via-Gmane: http://gmane.org/
To: python-list@python.org
From: Peter Otten <__peter__@web.de>
Subject: Re: numpy array operation
Date: Tue, 29 Jan 2013 10:28:02 +0100
Organization: None
References: <f94d7654-2b87-404b-a0b0-76f1ccf8ee6c@googlegroups.com>
Mime-Version: 1.0
Content-Type: text/plain; charset="ISO-8859-1"
Content-Transfer-Encoding: 7Bit
X-Gmane-NNTP-Posting-Host: p50849864.dip.t-dialin.net
User-Agent: KNode/4.7.3
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.1167.1359451658.2939.python-list@python.org>
Lines: 29
NNTP-Posting-Host: 2001:888:2000:d::a6
X-Trace: 1359451658 news.xs4all.nl 6921 [2001:888:2000:d::a6]:33013
X-Complaints-To: abuse@xs4all.nl
Xref: csiph.com comp.lang.python:37856

C. Ng wrote:

> Is there a numpy operation that does the following to the array?
> 
> 1 2  ==>  4 3
> 3 4       2 1

How about

>>> a
array([[1, 2],
       [3, 4]])
>>> a[::-1].transpose()[::-1].transpose()
array([[4, 3],
       [2, 1]])

Or did you mean

>>> a.reshape((4,))[::-1].reshape((2,2))
array([[4, 3],
       [2, 1]])

Or even

>>> -a + 5
array([[4, 3],
       [2, 1]])