On 03/20/15 at 01:46pm, Mr. Twister wrote:
> I have two numpy arrays:
>
> >>> P
> array([[[ 2, 3],
> [33, 44],
> [22, 11],
> [ 1, 2]]])
> >>> R
> array([0, 1, 2, 3])
>
> the values of these may of course be different. The important fact is that:
>
> >>> P.shape
> (1, 4, 2)
> >>> R.shape
> (4,)
>
> where the number 4 in the shape of both P and R may be another number as well
> (same on both).
>
>
> What I'd like to get is a new array Q with same shape as P so that the nth
> pair
> of Q is the nth pair of P multiplied by the nth element of R. I.e., in the
> above
> case it should produce:
>
> >>> Q
> array([[[ 0, 0],
> [33, 44],
> [44, 22],
> [ 3, 6]]])
>
>
> Is there a direct, single expression command to get this result?
I think that you want
P * R[;,None]
Read about broadcasting
(http://docs.scipy.org/doc/numpy/user/basics.broadcasting.html) for an
explanation. I'm never sure I understand it myself :)
Manolo
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