python - 如何安装 itertools 包？

Question

我想试试permutations来自 itertools 的函数模块。但是每次我尝试实现它时，我都会收到以下错误:
代码:

from itertools import permutations

txt=permutations('SKIN')
print(txt)

输出:

<itertools.permutations object at 0x7fee48665950>

我尝试使用命令 pip install itertools在我的命令提示符下，但我不断收到错误消息:

ERROR: Could not find a version that satisfies the requirement itertools (from versions: none)
ERROR: No matching distribution found for itertools

如何安装软件包？

Answer 1

itertools 是一个内置模块，无需安装:

Help on module itertools:

NAME
    itertools - Functional tools for creating and using iterators.

FILE
    /usr/lib64/python2.7/lib-dynload/itertoolsmodu

permutations(<iterable>)返回一个生成器，它产生可迭代中元素的连续 r 长度排列:

>>> type(txt)
<type 'itertools.permutations'>

>>> dir(txt)
['__class__', '__delattr__', '__doc__', '__format__', '__getattribute__', '__hash__', '__init__', '__iter__', '__new__', '__reduce__', '__reduce_ex__', '__repr__', '__setattr__', '__sizeof__', '__str__', '__subclasshook__', 'next']

所需排列列表:

list_perms = [ "".join(i) for i in permutations("SKIN")]

# ['SKIN', 'SKNI', 'SIKN', 'SINK', 'SNKI', 'SNIK', 'KSIN', 'KSNI', 'KISN', 'KINS', 'KNSI', 'KNIS', 'ISKN', 'ISNK', 'IKSN', 'IKNS', 'INSK', 'INKS', 'NSKI', 'NSIK', 'NKSI', 'NKIS', 'NISK', 'NIKS']