[SciPy-user] extracting elements of a matrix using arrays as indices

Fabrice Silva silva@lma.cnrs-mrs...
Tue May 20 16:51:00 CDT 2008


Le mardi 20 mai 2008 à 08:03 -0600, Michael Hearne a écrit :
> In Python:
> a = array([[ 11, 12, 13, 14 ],
> [ 21, 22, 23, 24 ],
> [ 31, 32, 33, 34 ]])
> a[[0,2],[0,3]]
> gives you:
> array([11, 34])

> So, I have two questions:
> 1) How do I actually get the equivalent behavior in Python?

>>> from numpy import array
>>> a = array([[ 11, 12, 13, 14 ],
... [ 21, 22, 23, 24 ],
... [ 31, 32, 33, 34 ]])

>>> a[:,[0,3]][[0,2],:]
array([[11, 14],
       [31, 34]])

>>> a[[0,2],[0,3]]
array([11, 34])

-- 
Fabrice Silva <silva@lma.cnrs-mrs.fr>
LMA UPR CNRS 7051 - équipe S2M



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