Question

我有一份使用<代码>itertools.product的3条文字,但我需要能够用只安装了python 2.4的机器操作。由于itertools.product 是第2.6页新写的,我不再能够利用这一功能。

How can I emulate itertools.product in Python 2.4 in a pythonic way?

Answer 1

I m 不太熟悉python 2.4,但

This function is equivalent to the following code, except that the actual implementation does not build up intermediate results in memory:

def product(*args, **kwds):
    # product( ABCD ,  xy ) --> Ax Ay Bx By Cx Cy Dx Dy
    # product(range(2), repeat=3) --> 000 001 010 011 100 101 110 111
    pools = map(tuple, args) * kwds.get( repeat , 1)
    result = [[]]
    for pool in pools:
        result = [x+[y] for x in result for y in pool]
    for prod in result:
        yield tuple(prod)

Answer 2

http://docs.python.org/library/itertools.html#itertools.product” rel=“noreferer” http://docs.python.org/library/itertools.html#itertools.product。

def product(*args, **kwds):
    # product( ABCD ,  xy ) --> Ax Ay Bx By Cx Cy Dx Dy
    # product(range(2), repeat=3) --> 000 001 010 011 100 101 110 111
    pools = map(tuple, args) * kwds.get( repeat , 1)
    result = [[]]
    for pool in pools:
        result = [x+[y] for x in result for y in pool]
    for prod in result:
        yield tuple(prod)

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