Say I have these three lists:
a = [1, 2, 3, 4]
b = [5, 6, 7, 8, 9]
c = [10, 11, 12]
Is there a builtin function such that:
No there isn't, but you can easily combine the functionality of takewhile and izip_longest to achieve what you want
from itertools import takewhile, izip_longest
from operator import itemgetter
somezip = lambda *p: list(takewhile(itemgetter(0),izip_longest(*p)))
(In case the first-iterator may have items which evaluates to False, you can replace the itemgetter with a lambda expression - refer @ovgolovin's comment)
somezip = lambda *p: list(takewhile(lambda e: not e[0] is None,izip_longest(*p)))
Examples
>>> from itertools import takewhile, izip_longest
>>> from operator import itemgetter
>>> a = [1, 2, 3, 4]
>>> b = [5, 6, 7, 8, 9]
>>> c = [10, 11, 12]
>>> somezip(a,b)
[(1, 5), (2, 6), (3, 7), (4, 8)]
>>> somezip(a,c)
[(1, 10), (2, 11), (3, 12), (4, None)]
>>> somezip(b,c)
[(5, 10), (6, 11), (7, 12), (8, None), (9, None)]