numpy: frequencies

Filip Wasilewski filipwasilewski at
Sat Nov 18 15:31:40 CET 2006

robert wrote:
> I have an integer array with values limited to range(a,b) like:
> ia=array([1,2,3,3,3,4,...2,0,1])
> and want to speedly count the frequencies of the integers into get a density matrix.
> Is this possible without looping?

See numpy.bincount (for integers >= 0) if you mean 'without writing
looping code in Python' or please specify your question.

> Question 2: is it possible to compute a "moving maximum" without python looping
> ia=array([4,2,1,5,3,2,2,0,1,1])
> -> mvmax(ia,3) ->
>          [4,4,4,5,5,5,3,2,2,1])

I haven't seen a ready solution but this can be easily converted into
Pyrex/C looping.


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