[Numpy-discussion] how to use argsort result?
Emanuele Olivetti
olivetti at itc.it
Tue Jul 11 04:32:48 CDT 2006
Hi,
I don't understand how to use argsort results. I have a 2D matrix and
I want to sort values in each row and obtain the index array of that
sorting. Argsort(1) is what I need, but the problem is how to use its
result in order to obtain a sorted matrix. Here is the simple example:
A = array([[2,3,1],[5,4,6]])
indexes = a.argsort(1)
now indexes is:
array([[2, 0, 1],
[1, 0, 2]])
I'd like to apply indexes to A and obtain:
array([[1, 2, 3],
[4, 5, 6]])
or better, I'm interested both in a subset of indexes, i.e. indexes[:,1:], and
the related values of A matrix.
How can I do this? If I simpy say: A[indexes] I get an IndexError.
Thanks in advance,
Emanuele
P.S. numpy.__version__ is '0.9.8'.
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