python 3.2笔记 zip()函数

先看文档：zip(*iterables)

Make an iterator that aggregates elements from each of the iterables.
Returns an iterator of tuples, where the i-th tuple contains the
i-th element from each of the argument sequences or iterables. The
iterator stops when the shortest input iterable is exhausted. With a single
iterable argument, it returns an iterator of 1-tuples. With no arguments, it
returns an empty iterator. Equivalent to:
def zip(*iterables):
    # zip('ABCD', 'xy') --> Ax By
    sentinel = object()
    iterables = [iter(it) for it in iterables]
    while iterables:
        result = []
        for it in iterables:
            elem = next(it, sentinel)
            if elem is sentinel:
                return
            result.append(elem)
        yield tuple(result)
举例：
>>> k = list(zip(*[[1,2,3],[4,5,6]]))
>>> k
[(1, 4), (2, 5), (3, 6)]

zip()是内置函数， 能把迭代对象进行聚合，返回值是迭代对象-聚合后的元组，用list()函数把它转化为列表

文档那个等价函数值得学习，那个iter()、next()用法并不简单。