count() 会创建一个无限的迭代器

“` import itertools ns = itertools.count(1) for n in ns: PRint(ns)

nu = itertools.count(1) ns = itertools.takewhile(lambda x: x <= 10, nu) list(ns) [1, 2, 3, 4, 5, 6, 7, 8, 9, 10]

ns = itertools.cycle(‘abx’) for n in ns: print(ns)

ns = itertools.repeat(‘abc’,3) for n in ns: print(ns)

for c in itertools.chain(‘ABC’, ‘XYZ’): print（c）

迭代效果：’A’ ‘B’ ‘C’ ‘X’ ‘Y’ ‘Z’

for key,group itertools.chain(‘aaafferrrty’): print(key,list(group) “`

感觉好无聊的，不知道在哪呀，希望用的时候可以想起来