How to merge two generators in between?

Question

How can I merge two different generators, in a way that in every iteration, a different generator will get yield?

>>> gen = merge_generators_in_between("ABCD","12")
>>> for val in gen:
...     print val
A
1
B
2
C
D

How can I achieve this? I didn't find a function for it in itertools.

Answer 1

Look in the itertools recipes under round robin:

>>> from itertools import cycle, islice
>>> def roundrobin(*iterables):
        "roundrobin('ABC', 'D', 'EF') --> A D E B F C"
        # Recipe credited to George Sakkis
        pending = len(iterables)
        nexts = cycle(iter(it).next for it in iterables)
        while pending:
            try:
                for next in nexts:
                    yield next()
            except StopIteration:
                pending -= 1
                nexts = cycle(islice(nexts, pending))


>>> for x in roundrobin("ABCD", "12"):
        print x


A
1
B
2
C
D