A way to compute a 2d histogram

Xavier Gnata gnata at obs.univ-lyon1.fr
Tue Oct 31 05:04:41 CST 2006


Hi,

Your histograms functions look fine for me :)
As it is a quite usual  operation on an array, I would suggest  to put 
it in numpy as numpy.histogram. IMHO, there is no point to create an 
numpy.stats only for histograms (or do you have plans to move other 
stats related function to numpy.stats?)

Xavier.

> Nicolas, thanks for the bug report, I fooled around with argument 
> passing and should have checked every case.
>
> You'll find the histogram function that deals with weights on the 
> numpy trac ticket 189, <http://projects.scipy.org/scipy/numpy/ticket/189>
> I'm waiting for some hints as to where the histogram function should 
> reside (numpy.histogram, numpy.stats.histogram, ...) before submitting 
> a patch .
>
> Salut,
> David
>
>
> 2006/10/25, Nicolas Champavert <nicolas.champavert at obs.univ-lyon1.fr 
> <mailto:nicolas.champavert at obs.univ-lyon1.fr>>:
>
>     Hi,
>
>         it would be great if you could add the weight option in the 1D
>     histogram too.
>
>     Nicolas
>
>     David Huard a écrit :
>     > Xavier,
>     > Here is the patch against svn. Please report any bug. I haven't had
>     > the time to test it extensively, something that should be done
>     before
>     > commiting the patch to the repo. I'd appreciate your feedback.
>     >
>     > David
>     >
>     > 2006/10/24, David Huard < david.huard at gmail.com
>     <mailto:david.huard at gmail.com>
>     > <mailto:david.huard at gmail.com <mailto:david.huard at gmail.com>>>:
>     >
>     >     Hi Xavier,
>     >
>     >     You could tweak histogram2d to do what you want, or you
>     could give
>     >     me a couple of days and I'll do it and let you know. If you want
>     >     to help, you could write a test using your particular
>     application
>     >     and data.
>     >
>     >     David
>     >
>     >
>     >     2006/10/24, Xavier Gnata < gnata at obs.univ-lyon1.fr
>     <mailto:gnata at obs.univ-lyon1.fr>
>     >     <mailto:gnata at obs.univ-lyon1.fr
>     <mailto:gnata at obs.univ-lyon1.fr>>>:
>     >
>     >         Hi,
>     >
>     >         I have a set of 3 1D large arrays.
>     >         The first 2 one stand for the coordinates of particules and
>     >         the last one
>     >         for their masses.
>     >         I would like to be able to plot this data ie to compute
>     a 2D
>     >         histogram
>     >         summing the masses in each bin.
>     >         I cannot find a way to do that without any loop on the
>     indices
>     >         resulting
>     >         too a very slow function.
>     >
>     >         I'm looking for an elegant way to do that with numpy (or
>     >         scipy??) function.
>     >
>     >         For instance, scipy.histogram2d cannot do the job because it
>     >         only counts
>     >         the number of samples in each bin.
>     >         There is no way to deal with weights.
>     >
>     >         Xavier.
>     >
>     >
>     >         --
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>     >         Xavier Gnata
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>     <mailto:gnata at obs.univ-lyon1.fr> <mailto:gnata at obs.univ-lyon1.fr
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-- 
############################################
Xavier Gnata
CRAL - Observatoire de Lyon
9, avenue Charles André
69561 Saint Genis Laval cedex
Phone: +33 4 78 86 85 28
Fax: +33 4 78 86 83 86
E-mail: gnata at obs.univ-lyon1.fr
############################################ 


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