Path: csiph.com!fu-berlin.de!uni-berlin.de!not-for-mail From: Peter Otten <__peter__@web.de> Newsgroups: comp.lang.python Subject: Re: why x is changed in the following program? Date: Fri, 18 Mar 2016 11:37:16 +0100 Organization: None Lines: 19 Message-ID: References: <81574A74-81F6-44F3-8A42-EC3B12A2A399@telecom-paristech.fr> Mime-Version: 1.0 Content-Type: text/plain; charset="ISO-8859-1" Content-Transfer-Encoding: 7Bit X-Trace: news.uni-berlin.de HOJ9p4JrGGauftYmPyeHjQg1IcCMmgOqqJiWT8afdL3g== Return-Path: 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; 'received:80.91': 0.09; 'received:80.91.229': 0.09; 'received:gmane.org': 0.09; 'received:list': 0.09; 'subject:why': 0.09; 'python': 0.10; 'modification': 0.15; 'numpy': 0.16; 'received:80.91.229.3': 0.16; 'received:dip0.t-ipconnect.de': 0.16; 'received:io': 0.16; 'received:plane.gmane.org': 0.16; 'received:psf.io': 0.16; 'received:t-ipconnect.de': 0.16; 'subject:program': 0.16; 'wrote:': 0.16; 'affects': 0.22; 'object.': 0.22; 'import': 0.24; 'header:User-Agent:1': 0.26; "doesn't": 0.26; 'header:X -Complaints-To:1': 0.26; 'random': 0.29; 'print': 0.30; 'to:addr :python-list': 0.36; 'subject:?': 0.36; 'subject:: ': 0.37; 'received:org': 0.37; 'subject:the': 0.39; 'skip:x 10': 0.40; 'to:addr:python.org': 0.40; 'received:de': 0.40 X-Injected-Via-Gmane: http://gmane.org/ X-Gmane-NNTP-Posting-Host: p57bd8b3b.dip0.t-ipconnect.de User-Agent: KNode/4.13.3 X-BeenThere: python-list@python.org X-Mailman-Version: 2.1.21 Precedence: list List-Id: General discussion list for the Python programming language List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Xref: csiph.com comp.lang.python:105194 maurice.charbit@telecom-paristech.fr wrote: > from numpy import random > x=random.randn(6) In Python > y=x doesn't make a copy, it binds y to the same object as x. From now on every modification you apply to y > y[0]=12 affects x, too, because x and y refer to the same object. > print x[0]