__main__.py 文件源码

def combinations_with_replacement(iterable, r):
        """
        >>> list(combinations_with_replacement('AT', 2))
        [('A', 'A'), ('A', 'T'), ('T', 'T')]
        """
        assert isinstance(r, (int, long))
        assert r >= 0

        if r == 0:
            yield ()
        else:
            alls = list(iterable)
            for (i, el) in enumerate(alls):
                for els in combinations_with_replacement(alls[i:], r - 1):
                    yield (el,) + els