[Numpy-discussion] how do I list all combinations

[Mathew Yeates]

Hi
I've been looking at "fromfunction" and itertools but I'm flummoxed.

I have an arbitrary number of lists. I want to form all possible 
combinations from all lists. So if
r1=["dog","cat"]
r2=[1,2]

I want to return [["dog",1],["dog",2],["cat",1],["cat",2]]

It's obvious when the number of lists is not arbitrary. But what if 
thats not known until runtime?

Mathew