[Python知识库]Python使用itertools创建迭代器的简易教程

链接：https://docs.python.org/3/library/itertools.html#itertools.cycle

创建一个等步长计数的迭代器

import numpy as np
import itertools as it
start=1
step_size=3.14
counter=it.count(start,step_size)
print([next(counter) for i in range(10)])

结果：

[1, 4.140000000000001, 7.280000000000001, 10.420000000000002, 13.560000000000002, 16.700000000000003, 19.840000000000003, 22.980000000000004, 26.120000000000005, 29.260000000000005]

创建一个环形迭代器

import numpy as np
import itertools as it

cyc=it.cycle([1,2,3])
print([next(cyc) for i in range(10)])

创建一个permutation迭代器

import numpy as np
import itertools as it
cyc=it.permutations(['A','B','C'],2)
print(list(cyc))

结果：

[('A', 'B'), ('A', 'C'), ('B', 'A'), ('B', 'C'), ('C', 'A'), ('C', 'B')]