[Numpy-discussion] "Extended" Outer Product
Christopher Barker
Chris.Barker at noaa.gov
Mon Aug 20 19:51:55 EDT 2007
Robert Kern wrote:
> If you can code your function such that it only uses operations that broadcast
> (i.e. operators and ufuncs) and avoids things like branching or loops, then you
> can just use numpy.newaxis on the first array.
>
> from numpy import array, newaxis
> x = array([1, 2, 3])
> y = array([10, 100, 1000])
> f(x[:,newaxis], y)
in fact, it may make sense to just have your x be column vector anyway:
>>> x
array([1, 2, 3])
>>> y
array([10, 11, 12])
>>> x.shape = (-1,1)
>>> x
array([[1],
[2],
[3]])
>>> x * y
array([[10, 11, 12],
[20, 22, 24],
[30, 33, 36]])
Broadcasting is VERY cool!
-Chris
--
Christopher Barker, Ph.D.
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Chris.Barker at noaa.gov
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