itertools

无穷循环器

import itertools

a = itertools.count(5,2)  #从5开始的整数循环器，每次增加2，即5, 7, 9, 11, 13, 15 ...
print(a.__next__())
print(a.__next__())
print(a.__next__())
print(a.__next__())
>>>
5
7
9
11

a = itertools.cycle("abc")  #重复序列的元素，既a, b, c, a, b, c ...
print(a.__next__())
print(a.__next__())
print(a.__next__())
print(a.__next__())
>>>>
a
b
c
a

a = itertools.repeat(10,4)  #重复10，共重复4次
print(a.__next__())
print(a.__next__())
print(a.__next__())
print(a.__next__())
>>>>
10
10
10
10