On 8/20/07, Geoffrey Zhu <zyzhu2000@gmail.com> wrote:
Hi Everyone,
I am wondering if there is an "extended" outer product. Take the example in "Guide to Numpy." Instead of doing an multiplication, I want to call a custom function for each pair.
print outer([1,2,3],[10,100,1000])
[[ 10 100 1000] [ 20 200 2000] [ 30 300 3000]]
So I want:
[ [f(1,10), f(1,100), f(1,1000)], [f(2,10), f(2, 100), f(2, 1000)], [f(3,10), f(3, 100), f(3,1000)] ]
You could make two matrices like so: In [46]: a = arange(3) In [47]: b = a.reshape(1,3).repeat(3,0) In [48]: c = a.reshape(3,1).repeat(3,1) In [49]: b Out[49]: array([[0, 1, 2], [0, 1, 2], [0, 1, 2]]) In [50]: c Out[50]: array([[0, 0, 0], [1, 1, 1], [2, 2, 2]]) which will give you all pairs. You can then make a function of these in various ways, for example In [52]: c**b Out[52]: array([[1, 0, 0], [1, 1, 1], [1, 2, 4]]) That is a bit clumsy, though. I don't know how to do what you want in a direct way. Chuck