该itertools例子提供了
window，不只是该函数：
from itertools import islicedef window(seq, n=2): "Returns a sliding window (of width n) over data from the iterable" " s -> (s0,s1,...s[n-1]), (s1,s2,...,sn), ... " it = iter(seq) result = tuple(islice(it, n)) if len(result) == n: yield result for elem in it: result = result[1:] + (elem,) yield result
用法示例：
>>> ["".join(x) for x in window("7316717", 3)]['731', '316', '167', '671', '717']
