[SciPy-user] extracting elements of a matrix using arrays as indices
Alan G Isaac
Wed May 21 14:29:35 CDT 2008
On Tue, May 20, 2008 at 9:43 PM, Michael Hearne <email@example.com> wrote:
> Neilen - Thanks. Unfortunately, I've either discovered
> a bug or have failed to understand how to use this
> function. The below code snippet:
> from pylab import *
> import numpy
> print numpy.__version__, numpy.__file__
> data = rand(648,690)
> i,j = (data < 0.14).nonzero()
> data[ix_(i,j)] = data[ix_(i,j)]*0
I believe your problem is with ``data[ix_(i,j)]``.
Let's say that i and j are about 60,000 in length.
So you are trying to create a 60k × 60k array,
which has 3600M elements. I'm guessing you do not
have enough memory for this. Otherwise, it should
work (although it is very wasteful).
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