All possible variants of zip in Python

Question

For example, I have a code looks like this:

a = [1, 2]
b = [4, 5]

How can I get something like this:

[(1,4), (1,5), (2,4), (2,5         


        

Answer 1

If you're interested only in the result, then itertools.product is what you need (+1 to @DSM for this). However, if you're interested in the algorithm that generates something like this, it's called recursive descent. The algorithm, in this case, would run as follows (I'm just going to print the results here for clarity):

def product(L, tmp=None):
    if tmp is None:
        tmp = []
    if L==[]:
        print tmp
    else:
        for i in L[0]:
            product(L[1:], tmp+[i])

Thus,

>>> product([[1,2], [4,5]])
[1, 4]
[1, 5]
[2, 4]
[2, 5]

Hope this helps