matching elements of numeric arrays

[daniel.neilson at gmail.com]

I have two one-dimensional Numeric arrays, and I need to know the
indices in the second array of elements from the first.

so if i had:

a=array([2,4,6])
b=array([2,3,4,5,6])

i want a function match that does this:

>>> match(a,b)
array([0,2,4])

i have something that works, but it involves converting things to lists
and using 'in', and it is rather slow. if someone could point me to a
better solution, i would appreciate it.