Groups | Search | Server Info | Keyboard shortcuts | Login | Register [http] [https] [nntp] [nntps]

Groups > comp.lang.python > #104514

Re: looping and searching in numpy array

Path csiph.com!fu-berlin.de!uni-berlin.de!not-for-mail
From Mark Lawrence <breamoreboy@yahoo.co.uk>
Newsgroups comp.lang.python
Subject Re: looping and searching in numpy array
Date Thu, 10 Mar 2016 13:22:14 +0000
Lines 29
Message-ID <mailman.129.1457616312.15725.python-list@python.org> (permalink)
References <77bd470b-cc05-4117-9ed1-6309d7a5633a@googlegroups.com>
Mime-Version 1.0
Content-Type text/plain; charset=windows-1252; format=flowed
Content-Transfer-Encoding 7bit
X-Trace news.uni-berlin.de Dbz3jBcqNR7YvB045hjamQdUx9su/Kic47XwdpzJ1HUg==
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 0.001
X-Spam-Evidence '*H*': 1.00; '*S*': 0.00; 'from:addr:yahoo.co.uk': 0.05; 'below)': 0.07; 'before.': 0.09; 'received:80.91': 0.09; 'received:80.91.229': 0.09; 'received:gmane.org': 0.09; 'received:list': 0.09; 'anyway': 0.11; 'size,': 0.13; 'suggest': 0.15; 'expert,': 0.16; 'numpy': 0.16; 'received:80.91.229.3': 0.16; 'received:io': 0.16; 'received:plane.gmane.org': 0.16; 'received:psf.io': 0.16; 'subject:array': 0.16; 'subject:looping': 0.16; 'wrote:': 0.16; 'language': 0.19; 'all,': 0.20; 'arrays': 0.22; 'lawrence': 0.22; 'seems': 0.23; 'bigger': 0.23; "haven't": 0.24; 'header:In-Reply-To:1': 0.24; 'script': 0.25; 'header:User- Agent:1': 0.26; 'example': 0.26; 'header:X-Complaints-To:1': 0.26; 'question': 0.27; 'search.': 0.29; 'array': 0.29; 'asked': 0.29; "i'm": 0.30; 'guess': 0.31; 'help,': 0.32; 'language.': 0.32; 'run': 0.33; 'values.': 0.33; 'list': 0.34; 'but': 0.36; 'there': 0.36; 'lines': 0.36; 'to:addr:python-list': 0.36; 'subject:: ': 0.37; 'two': 0.37; 'there,': 0.37; 'thanks': 0.37; 'received:org': 0.37; 'doing': 0.38; 'mailing': 0.38; 'to:addr:python.org': 0.40; 'mark': 0.40; 'your': 0.60; 'charset:windows-1252': 0.62; 'above,': 0.63; 'necessarily': 0.63; 'our': 0.64; 'dear': 0.67; 'pythonistas,': 0.84
X-Injected-Via-Gmane http://gmane.org/
X-Gmane-NNTP-Posting-Host 80.234.129.0
User-Agent Mozilla/5.0 (Windows NT 10.0; WOW64; rv:38.0) Gecko/20100101 Thunderbird/38.6.0
In-Reply-To <77bd470b-cc05-4117-9ed1-6309d7a5633a@googlegroups.com>
X-BeenThere python-list@python.org
X-Mailman-Version 2.1.21
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>
Xref csiph.com comp.lang.python:104514

Show key headers only | View raw

On 10/03/2016 11:43, Heli wrote:
> Dear all,
>
> I need to loop over a numpy array and then do the following search. The following is taking almost 60(s) for an array (npArray1 and npArray2 in the example below) with around 300K values.
>
>
> for id in np.nditer(npArray1):
>
>         newId=(np.where(npArray2==id))[0][0]
>
>
> Is there anyway I can make the above faster? I need to run the script above on much bigger arrays (50M). Please note that my two numpy arrays in the lines above, npArray1 and npArray2  are not necessarily the same size, but they are both 1d.
>
>
> Thanks a lot for your help,
>

I'm no numpy expert, but if you're using a loop my guess is that you're 
doing it wrong.  I suggest your first port of call is the numpy docs if 
you haven't all ready been there, then the specific numpy mailing list 
or stackoverflow, as it seems very likely that this type of question has 
been asked before.

-- 
My fellow Pythonistas, ask not what our language can do for you, ask
what you can do for our language.

Mark Lawrence

Back to comp.lang.python | Previous | Next — Previous in thread | Next in thread | Find similar | Unroll thread

Thread

looping and searching in numpy array Heli <hemla21@gmail.com> - 2016-03-10 03:43 -0800
  Re: looping and searching in numpy array Peter Otten <__peter__@web.de> - 2016-03-10 14:02 +0100
    Re: looping and searching in numpy array Heli <hemla21@gmail.com> - 2016-03-10 08:48 -0800
      Re: looping and searching in numpy array Heli <hemla21@gmail.com> - 2016-03-10 08:50 -0800
      RE: looping and searching in numpy array Albert-Jan Roskam <sjeik_appie@hotmail.com> - 2016-03-13 13:51 +0000
      RE: looping and searching in numpy array Albert-Jan Roskam <sjeik_appie@hotmail.com> - 2016-03-13 15:43 +0000
  Re: looping and searching in numpy array Mark Lawrence <breamoreboy@yahoo.co.uk> - 2016-03-10 13:22 +0000
  Re: looping and searching in numpy array srinivas devaki <mr.eightnoteight@gmail.com> - 2016-03-14 10:19 +0530
  Re: looping and searching in numpy array Oscar Benjamin <oscar.j.benjamin@gmail.com> - 2016-03-14 15:22 +0000

csiph-web