[Numpy-discussion] Selecting columns of a matrix (original) (raw)

Keith Goodman kwgoodman at gmail.com
Wed Jun 21 10:13:54 EDT 2006

On 6/20/06, Bill Baxter <wbaxter at gmail.com> wrote:

>>> a[:,num.where(v>0.5)[0]] array([[1, 2, 4], [6, 7, 9]])

I'll put that up on the Matlab->Numpy page.

That's a great addition to the Matlab to Numpy page.

But it only works if v is a column vector. If v is a row vector, then where(v.A > 0.5)[0] will return all zeros. So for row vectors it should be where(v.A > 0.5)[1].

Or, in general, where(v.flatten(1).A > 0.5)[1]

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