Path: csiph.com!usenet.pasdenom.info!aioe.org!news.stack.nl!newsfeed.xs4all.nl!newsfeed3a.news.xs4all.nl!xs4all!news.tele.dk!news.tele.dk!small.news.tele.dk!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 0.005
X-Spam-Evidence: '*H*': 0.99; '*S*': 0.00; 'skip:` 10': 0.07; 'subject:Question': 0.07; 'append': 0.09; 'received:80.91': 0.09; 'received:80.91.229': 0.09; 'received:gmane.org': 0.09; 'received:list': 0.09; 'python': 0.11; 'jan': 0.12; 'assume': 0.14; 'check.': 0.16; 'curious.': 0.16; 'received:80.91.229.3': 0.16; 'received:plane.gmane.org': 0.16; 'reedy': 0.16; 'subject:`': 0.16; 'wrote:': 0.18; 'memory': 0.22; 'header:User- Agent:1': 0.23; 'header:X-Complaints-To:1': 0.27; 'header:In- Reply-To:1': 0.27; "i'm": 0.30; '(which': 0.31; 'there,': 0.34; 'but': 0.35; 'hi,': 0.36; 'list': 0.37; 'depends': 0.38; 'to:addr :python-list': 0.38; 'pm,': 0.38; 'sure': 0.39; 'to:addr:python.org': 0.39; 'enough': 0.39; 'received:org': 0.40; 'easy': 0.60; 'entire': 0.61; 'received:173': 0.61; 'first': 0.61; 'more': 0.64; 'saving': 0.69; '"it': 0.84; 'received:fios.verizon.net': 0.84
X-Injected-Via-Gmane: http://gmane.org/
To: python-list@python.org
From: Terry Reedy <tjreedy@udel.edu>
Subject: Re: Question about `list.insert`
Date: Thu, 06 Feb 2014 19:40:00 -0500
References: <4041bba7-91bc-4803-9150-2fcf14ecb5a9@googlegroups.com>
Mime-Version: 1.0
Content-Type: text/plain; charset=UTF-8; format=flowed
Content-Transfer-Encoding: 7bit
X-Gmane-NNTP-Posting-Host: pool-173-75-254-207.phlapa.fios.verizon.net
User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:24.0) Gecko/20100101 Thunderbird/24.3.0
In-Reply-To: <4041bba7-91bc-4803-9150-2fcf14ecb5a9@googlegroups.com>
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: <https://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: <https://mail.python.org/mailman/listinfo/python-list>, <mailto:python-list-request@python.org?subject=subscribe>
Newsgroups: comp.lang.python
Message-ID: <mailman.6465.1391733626.18130.python-list@python.org>
Lines: 16
NNTP-Posting-Host: 2001:888:2000:d::a6
X-Trace: 1391733626 news.xs4all.nl 2913 [2001:888:2000:d::a6]:49649
X-Complaints-To: abuse@xs4all.nl
Xref: csiph.com comp.lang.python:65567

On 2/6/2014 6:59 PM, cool-RR wrote:
> Hi,
>
> I'm curious. If I append an item to a list from the left using
> `list.insert`, will Python always move the entire list one item to
> the right (which can be super-slow) or will it check first to see
> whether it can just allocate more memory to the left of the list and
> put the item there, saving a lot of resources?

"It depends on the implementation"

Assume O(n), which I am sure it is for CPython,  but easy enough to check.

-- 
Terry Jan Reedy