[Numpy-discussion] indexing bug in numpy r2694 (original) (raw)

Pau Gargallo pau.gargallo at gmail.com
Wed Jun 28 14:25:14 EDT 2006

On 6/28/06, Keith Goodman <kwgoodman at gmail.com> wrote:

On 6/28/06, Pau Gargallo <pau.gargallo at gmail.com> wrote: > i don't know why 'where' is returning matrices. > if you use: > > >>> idx = where(y.A > 0.5)[0] > > everything will work fine (I guess)

What about the second issue? Is this expected behavior? >> idx array([0, 1, 2]) >> y matrix([[ 0.63731308], [ 0.34282663], [ 0.53366791]]) >> y[idx] matrix([[ 0.63731308], [ 0.34282663], [ 0.53366791]]) >> y[idx,0] matrix([[ 0.63731308, 0.34282663, 0.53366791]]) I was expecting a column vector. I have never played with matrices, but if y was an array, y[idx,0] will be an array of the same shape of idx. That is a 1d array. I guess that when y is a matrix, this 1d array is converted to a matrix and become a row vector.

I don't know if this behaviour is wanted :-(

cheers, pau

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