如何在两者之间合并两台发电机？

Question

如何合并两个不同的生成器，在每次迭代中，不同的生成器都会获得收益？

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

我怎样才能做到这一点？我在itertools中没有找到它的功能。

Answer 1

查看循环下的itertools recipes：

>>> 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