Python基础 itertools

itertools

Python的内建模块itertools提供了非常有用的用于操作迭代对象的函数。

无限迭代器

itertools.count 不停打印自然数

示例代码

#!/usr/bin/env python3# -*- coding: utf-8 -*-# Python基础 itertoolsimport itertools# 无限迭代器natuals = itertools.count(1)for n in natuals:    # 不停打印自然数    print(n)

运行结果

D:\PythonProject>python main.py1234567无限打印

itertools.cycle 不停循环打印

运行示例

#!/usr/bin/env python3# -*- coding: utf-8 -*-# Python基础 itertoolsimport itertools# 无限迭代器cs = itertools.cycle("xyz")for c in cs:    print(c)

运行结果

.............xyzxyzxy...........

itertools.repeat 限定重复次数

运行示例

#!/usr/bin/env python3# -*- coding: utf-8 -*-# Python基础 itertoolsimport itertools# repeat 限定重复次数# 将good 重复3次打印cs = itertools.repeat("good", 3)for c in cs:    print(c)

运行结果

D:\PythonProject>python main.pygoodgoodgood

itertools.takewhile让无限变成有限序列

示例代码

#!/usr/bin/env python3# -*- coding: utf-8 -*-# Python基础 itertoolsimport itertools# takewhile让无限变成有限序列natuals = itertools.count(1)n = itertools.takewhile(lambda x:x<=10, natuals)ns = list(n)print(ns)

运行结果

D:\PythonProject>python main.py[1, 2, 3, 4, 5, 6, 7, 8, 9, 10]

chain 大迭代器 = 迭代器A + 迭代器 B

运行示例

#!/usr/bin/env python3# -*- coding: utf-8 -*-# Python基础 itertoolsimport itertools# chain 大迭代器 = 迭代器A + 迭代器 Bbig = itertools.chain("ABC","XYZ")for c in big:    print(c)

运行结果

D:\PythonProject>python main.pyABCXYZ

groupby挑出重复并分组

运行示例

#!/usr/bin/env python3# -*- coding: utf-8 -*-# Python基础 groupbyimport itertools# groupby挑出重复并分组data = "AAACCCCDDDDD"groupList = itertools.groupby(data)for key, group in groupList:    print(key, list(group))

运行结果

D:\PythonProject>python main.pyA ['A', 'A', 'A']C ['C', 'C', 'C', 'C']D ['D', 'D', 'D', 'D', 'D']