Re: looping in array vs looping in a dic

Path	csiph.com!usenet.pasdenom.info!gegeweb.org!de-l.enfer-du-nord.net!feeder1.enfer-du-nord.net!feeds.phibee-telecom.net!newsfeed.xs4all.nl!newsfeed5.news.xs4all.nl!xs4all!newsgate.cistron.nl!newsgate.news.xs4all.nl!post.news.xs4all.nl!not-for-mail
Return-Path	<python@mrabarnett.plus.com>
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; 'else:': 0.03; 'output': 0.04; 'mrab': 0.05; '%s"': 0.07; 'collections': 0.09; 'observation': 0.09; 'rows': 0.09; 'skip:v 70': 0.09; 'defaultdict': 0.16; 'from:addr:mrabarnett.plus.com': 0.16; 'from:addr:python': 0.16; 'from:name:mrab': 0.16; 'instead:': 0.16; 'message-id:@mrabarnett.plus.com': 0.16; 'received:84.93': 0.16; 'received:84.93.230': 0.16; 'row': 0.16; 'simple.': 0.16; 'skip:v 60': 0.16; 'subject:array': 0.16; 'subject:looping': 0.16; 'wrote:': 0.17; 'input': 0.18; 'code.': 0.20; 'question.': 0.20; 'import': 0.21; 'header:In-Reply-To:1': 0.25; 'header:User- Agent:1': 0.26; 'received:192.168.1.3': 0.29; 'file': 0.32; 'received:84': 0.32; 'could': 0.32; 'to:addr:python-list': 0.33; 'skip:d 20': 0.34; 'thanks': 0.34; 'add': 0.36; 'but': 0.36; 'should': 0.36; 'possible': 0.37; 'skip:v 20': 0.37; 'subject:: ': 0.38; 'to:addr:python.org': 0.39; 'received:192': 0.39; 'received:192.168': 0.40; 'skip:u 10': 0.60; 'first': 0.61; 'skip:n 10': 0.63; 'email addr:gmail.com': 0.63; 'more': 0.63; 'here': 0.65; 'sum': 0.66; 'header:Reply-To:1': 0.68; 'reply-to:no real name:2**0': 0.72; 'raster': 0.84; 'reply-to:addr:python.org': 0.84; 'subject:dic': 0.84; 'faster.': 0.91; 'average': 0.93
X-CM-Score	0.00
X-CNFS-Analysis	v=2.0 cv=asgw+FlV c=1 sm=1 a=0nF1XD0wxitMEM03M9B4ZQ==:17 a=AAvI7MrX_rgA:10 a=w7zqQIw9OgQA:10 a=ihvODaAuJD4A:10 a=OUOv7kDek9cA:10 a=8nJEP1OIZ-IA:10 a=EBOSESyhAAAA:8 a=8AHkEIZyAAAA:8 a=nTz416_S3dcA:10 a=pGLkceISAAAA:8 a=lh-EWxt6mCyF4nP2WQsA:9 a=wPNLvfGTeEIA:10 a=MSl-tDqOz04A:10 a=BS-JHms1EA6ew-4b:21 a=f6oXfQaS3mrghP3A:21 a=0nF1XD0wxitMEM03M9B4ZQ==:117
X-AUTH	mrabarnett:2500
Date	Fri, 21 Sep 2012 00:58:03 +0100
From	MRAB <python@mrabarnett.plus.com>
User-Agent	Mozilla/5.0 (Windows NT 5.1; rv:15.0) Gecko/20120907 Thunderbird/15.0.1
MIME-Version	1.0
To	python-list@python.org
Subject	Re: looping in array vs looping in a dic
References	<007b2d71-3355-4085-b84f-204834b2c8d0@googlegroups.com> <505B6A00.10308@mrabarnett.plus.com> <CALwzid=HowMzWmgiU2+2Gu4opxWu0Hx-iOFRZZcXi=BAdKVfrw@mail.gmail.com> <mailman.971.1348169395.27098.python-list@python.org> <f375e37c-d700-4ca5-b06b-2d195a5644de@googlegroups.com>
In-Reply-To	<f375e37c-d700-4ca5-b06b-2d195a5644de@googlegroups.com>
Content-Type	text/plain; charset=ISO-8859-1; format=flowed
Content-Transfer-Encoding	7bit
X-BeenThere	python-list@python.org
X-Mailman-Version	2.1.15
Precedence	list
Reply-To	python-list@python.org
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.984.1348185486.27098.python-list@python.org> (permalink)
Lines	42
NNTP-Posting-Host	2001:888:2000:d::a6
X-Trace	1348185486 news.xs4all.nl 6855 [2001:888:2000:d::a6]:47557
X-Complaints-To	abuse@xs4all.nl
Xref	csiph.com comp.lang.python:29587

Show key headers only | View raw

On 2012-09-21 00:35, giuseppe.amatulli@gmail.com wrote:
> Hi Ian and MRAB
> thanks to you input i have improve the speed  of my code. Definitely reading in dic() is faster. I have one more question.
> In the dic() I calculate the sum of the values, but i want count also the number of observation, in order to calculate the average in the end.
> Should i create a new dic() or is possible to do in the same dic().
> Here in the final code.
> Thanks Giuseppe
>
Keep it simple. Use 2 dicts.

>
>
> rows = dsCategory.RasterYSize
> cols = dsCategory.RasterXSize
>
> print("Generating output file %s" %(dst_file))
>
> start = time()
>
> unique=dict()
>
> for irows in xrange(rows):
>      valuesRaster=dsRaster.GetRasterBand(1).ReadAsArray(0,irows,cols,1)
>      valuesCategory=dsCategory.GetRasterBand(1).ReadAsArray(0,irows,cols,1)
>      for icols in xrange(cols):
>          if ( valuesRaster[0,icols] != no_data_Raster ) and ( valuesCategory[0,icols] != no_data_Category ) :
>              row = valuesCategory[0, icols],valuesRaster[0, icols]
>              if row[0] in unique :
>                  unique[row[0]] += row[1]
>              else:
>                  unique[row[0]] = 0+row[1] # this 0 was add if not the first observation was considered = 0
>
You could use defaultdict instead:

from collections import defaultdict

unique = defaultdict(int)
...
              category, raster = valuesCategory[0, icols], 
valuesRaster[0, icols]
              unique[category] += raster

Thread

looping in array vs looping in a dic giuseppe.amatulli@gmail.com - 2012-09-20 11:31 -0700
  Re: looping in array vs looping in a dic MRAB <python@mrabarnett.plus.com> - 2012-09-20 20:09 +0100
  Re: looping in array vs looping in a dic Ian Kelly <ian.g.kelly@gmail.com> - 2012-09-20 13:28 -0600
  Re: looping in array vs looping in a dic Ian Kelly <ian.g.kelly@gmail.com> - 2012-09-20 13:29 -0600
    Re: looping in array vs looping in a dic giuseppe.amatulli@gmail.com - 2012-09-20 16:35 -0700
      Re: looping in array vs looping in a dic MRAB <python@mrabarnett.plus.com> - 2012-09-21 00:58 +0100
    Re: looping in array vs looping in a dic giuseppe.amatulli@gmail.com - 2012-09-20 16:35 -0700

csiph-web