Question

I am new to python and my problem is the following:

I have defined a function func(a,b) that return a value, given two input values.

Now I have my data stored in lists or numpy arrays A,Band would like to use func for every combination. (A and B have over one million entries)

ATM i use this snippet:

for p in A:
  for k in B:
    value = func(p,k)

This takes really really a lot of time.

So i was thinking that maybe something like this:

C=(map(func,zip(A,B)))

But this method only works pairwise… Any ideas?

Thanks for help

Answer 1

suppose, itertools.product does what you need:

from itertools import product

pro = product(A,B)
C = map(lambda x: func(*x), pro)

so far as it is generator it doesn’t require additional memory