How can I run two generators at same time in python

Question

I want two generators yielding simultaneously, but any of them can be "hang" till the other one finishes.

def cal(tap):
        while (tap!=0):
            tap = tap-1
            yield tap

and I try to use the zip() to achieve but I got this as 7 and 5 for initial

     6 4
     5 3
     4 2
     3 1
     2 0

I want to achieve this:

     6 4
     5 3
     4 2
     3 1
     2 0
     1 0
     0 0

How can I do this? Do I need some support method or something?

Answer 1

Use itertools.zip_longest:

from itertools import zip_longest

g = zip_longest(cal(7), cal(5), fillvalue=0)

list(g)

Output:

[(6, 4), (5, 3), (4, 2), (3, 1), (2, 0), (1, 0), (0, 0)]