1.创建无限循环迭代对象:count,cycle,repeat
from itertools import count
for i in count(1, 2):
if i > 10:
break
print(i)
# 以1开始，2为步长，无限range结果：1 3 5 7 9
from itertools import cycle
colors = cycle(['red', 'green', 'blue'])
for i in range(6):
print(next(colors), end=",")
# 对给定的可迭代对象进行无限循环：red,green,blue,red,green,blue
from itertools import repeat
for i in repeat('hello', 3):
print(i)
# 重复hello这个对象。如果指定了times参数，就重复times次；如果不指定，就无限重复：
2.累加求和计算:accumulate
from itertools import accumulate numbers = [1, 2, 3, 4, 5] print(list(accumulate(numbers))) # 计算可迭代对象的累积结果。默认情况下，它计算的是累加和 # 示例：1、1 + 2、1+2+3、1+2+3 + 4、1+2+3+4+5的结果
3.拆分序列:chan
from itertools import chain
list1 = [1, 2, 3]
list2 = ['a', 'b', 'c']
for i in chain(list1, list2):
print(i)
# 先打印出list1中的元素 1、2、3，然后打印出list2中的元素a、b、c
4.筛选结果：dropwhile, takewhile
from itertools import dropwhile numbers = [1, 3, 5, 2, 4] result = dropwhile(lambda x: x % 2 == 1, numbers) print(list(result)) numbers = [1, 3, 5, 2, 4] result = filter(lambda x: x % 2 == 0, numbers) print(list(result))
from itertools import takewhile
numbers = [1, 3, 5, 2, 4] result = takewhile(lambda x: x % 2 == 1, numbers) print(list(result)) numbers = [1, 3, 5, 2, 4] result = filter(lambda x: x % 2 == 1, numbers) print(list(result))
5.全部自由组合:permutations,combinations,combinations_with_repalcement,pairwise
参数：选取几个字母组合，2就是2个字母
from itertools import permutations
letters = ['a', 'b', 'c']
print(list(permutations(letters, 2)))
#结果：[('a', 'b'), ('a', 'c'), ('b', 'a'), ('b', 'c'), ('c', 'a'), ('c', 'b')]
from itertools import combinations
letters = ['a', 'b', 'c']
print(list(combinations(letters, 2)))
#结果：[('a', 'b'), ('a', 'c'), ('b', 'c')]
from itertools import combinations_with_replacement
letters = ['a', 'b', 'c']
print(list(combinations_with_replacement(letters, 2)))
#结果：[('a', 'a'), ('a', 'b'), ('a', 'c'), ('b', 'b'), ('b', 'c'), ('c', 'c')]
from itertools import pairwise numbers = [1, 2, 3, 4, 5] pairs = pairwise(numbers) print(list(pairs)) #结果：[(1, 2), (2, 3), (3, 4), (4, 5)]