Re: How to make this faster

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Date	Fri, 5 Jul 2013 13:44:57 +0100
Subject	Re: How to make this faster
From	Fábio Santos <fabiosantosart@gmail.com>
To	Helmut Jarausch <jarausch@igpm.rwth-aachen.de>
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On 5 Jul 2013 11:58, "Helmut Jarausch" <jarausch@igpm.rwth-aachen.de> wrote:
>
> On Fri, 05 Jul 2013 11:13:33 +0100, Oscar Benjamin wrote:
>
> > My one comment is that you're not really making the most out of numpy
> > arrays. Numpy's ndarrays are efficient when each line of Python code
> > is triggering a large number of numerical computations performed over
> > the array. Because of their N-dimensional nature and the fact that
> > they are in some sense second class citizens in CPython they are often
> > not as good as lists for this kind of looping and indexing.
> >
> > I would actually expect this program to run faster with ordinary
> > Python lists and lists of lists. It means that you need to change e.g.
> > Grid[r, c] to Grid[r][c] but really I think that the indexing syntax
> > is all you're getting out of numpy here.
> >
>
> Thanks Oscar, that was a big improvement, indeed.
> Using lists of lists instead of numpy arrays made the code more than
> twice as fast (13 seconds down to 6 seconds)
>
> Since I don't do any numerical stuff with the arrays, Numpy doesn't seem
to be
> a good choice. I think this is an argument to add real arrays to Python.
>
> I even tried to use dictionaries instead of Numpy arrays. This version is
a bit
> slower then the lists of lists version (7.2 seconds instead of 6 second)
but still
> much faster than the Numpy array solution.

May I suggest you avoid range and use enumerate(the_array) instead? It
might be faster.

Thread

How to make this faster Helmut Jarausch <jarausch@igpm.rwth-aachen.de> - 2013-07-05 08:22 +0000
  Re: How to make this faster Fábio Santos <fabiosantosart@gmail.com> - 2013-07-05 10:38 +0100
  Re: How to make this faster Helmut Jarausch <jarausch@igpm.rwth-aachen.de> - 2013-07-05 10:07 +0000
  Re: How to make this faster Oscar Benjamin <oscar.j.benjamin@gmail.com> - 2013-07-05 11:13 +0100
  Re: How to make this faster Helmut Jarausch <jarausch@igpm.rwth-aachen.de> - 2013-07-05 10:53 +0000
    Re: How to make this faster Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2013-07-05 12:02 +0000
    Re: How to make this faster Fábio Santos <fabiosantosart@gmail.com> - 2013-07-05 13:44 +0100
    Re: How to make this faster Oscar Benjamin <oscar.j.benjamin@gmail.com> - 2013-07-05 14:41 +0100
    Re: How to make this faster Helmut Jarausch <jarausch@igpm.rwth-aachen.de> - 2013-07-05 14:28 +0000
      Re: How to make this faster Oscar Benjamin <oscar.j.benjamin@gmail.com> - 2013-07-05 15:45 +0100
    Re: How to make this faster Helmut Jarausch <jarausch@igpm.rwth-aachen.de> - 2013-07-05 14:48 +0000
      Re: How to make this faster Oscar Benjamin <oscar.j.benjamin@gmail.com> - 2013-07-05 16:26 +0100
    Re: How to make this faster Helmut Jarausch <jarausch@igpm.rwth-aachen.de> - 2013-07-05 14:54 +0000
      Re: How to make this faster Fábio Santos <fabiosantosart@gmail.com> - 2013-07-05 16:18 +0100
      Re: How to make this faster Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2013-07-05 16:24 +0000
    Re: How to make this faster Helmut Jarausch <jarausch@igpm.rwth-aachen.de> - 2013-07-05 15:17 +0000
      Re: How to make this faster Oscar Benjamin <oscar.j.benjamin@gmail.com> - 2013-07-05 16:38 +0100
      Re: How to make this faster MRAB <python@mrabarnett.plus.com> - 2013-07-05 17:25 +0100
      Re: How to make this faster Joshua Landau <joshua.landau.ws@gmail.com> - 2013-07-06 02:45 +0100
    Re: How to make this faster Helmut Jarausch <jarausch@igpm.rwth-aachen.de> - 2013-07-05 15:47 +0000
      Re: How to make this faster Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2013-07-05 16:52 +0000
    Re: How to make this faster Helmut Jarausch <jarausch@igpm.rwth-aachen.de> - 2013-07-05 16:07 +0000
      Re: How to make this faster Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2013-07-05 16:50 +0000
        Re: How to make this faster Helmut Jarausch <jarausch@igpm.rwth-aachen.de> - 2013-07-05 18:39 +0000
          Re: How to make this faster Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2013-07-06 03:05 +0000
          Re: How to make this faster Helmut Jarausch <jarausch@igpm.rwth-aachen.de> - 2013-07-06 07:25 +0000
    Re: How to make this faster Helmut Jarausch <jarausch@igpm.rwth-aachen.de> - 2013-07-05 18:42 +0000

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