[Numpy-discussion] addressing a submatrix

Simon Burton simon at arrowtheory.com
Wed Jun 14 13:25:55 CDT 2006


On Wed, 14 Jun 2006 11:14:17 +0200
Martin Wiechert <martin.wiechert at gmx.de> wrote:

> 
> Hi list,
> 
> is there a concise way to address a subrectangle of a 2d array? So far I'm 
> using
> 
> A [I] [:, J]

what about A[I,J] ?

Simon.

>>> import numpy
>>> a=numpy.zer
numpy.zeros       numpy.zeros_like  
>>> a=numpy.zeros([4,4])
>>> a
array([[0, 0, 0, 0],
       [0, 0, 0, 0],
       [0, 0, 0, 0],
       [0, 0, 0, 0]])
>>> a[2:3,2:3]=1
>>> a
array([[0, 0, 0, 0],
       [0, 0, 0, 0],
       [0, 0, 1, 0],
       [0, 0, 0, 0]])
>>> a[1:3,1:3]=1
>>> a
array([[0, 0, 0, 0],
       [0, 1, 1, 0],
       [0, 1, 1, 0],
       [0, 0, 0, 0]])
>>> 


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Simon Burton, B.Sc.
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