Python:迷你字母中所有固定长度的可能单词(排列) [英] Python: all possible words (permutations) of fixed length in mini-alphabet

问题描述

假设我有一个像这样的字符串:

Let's say I have a string like so:

abcdefghijklmnopqrstuvwxyz1234567890!@#$%^&*()-_+={}[]\:;"'?/>.<,`~|€

这基本上是键盘上所有字符的列表.我怎样才能得到一个由8个字符组成的单词"的所有可能组合?我知道将会有数以百万计的可能性.

This is basicly a list of all the characters on my keyboard. How could I get all possible combinations for, let's say, a "word" made up of 8 of these chars? I know there are going to be millions of possibilities.

干杯！

推荐答案

排列与组合之间的差异

您正在寻找排列或组合.

You are either looking for a permutation or a combination.

'abc'和'bac'是不同的排列，但是它们是相同的组合{a,b,c}.

'abc' and 'bac' are different permutations, but they are the same combination {a,b,c}.

'abc'的排列:''，'a'，'b'，'c'，'ab'，'ba'，'ac'，'ca'，'bc'，'cb'，'abc'，'acb'，'bac'，'bca'，'cab'，'cba'

Permutations of 'abc': '', 'a', 'b', 'c', 'ab', 'ba', 'ac', 'ca', 'bc', 'cb', 'abc', 'acb', 'bac', 'bca', 'cab', 'cba'

"abc"的组合:{}，{'a'}，{'b'}，{'c'}，{'a','b'}，{'b','c'}，{'a','c'}，{'a','b','c'}

Combinations of 'abc': {}, {'a'}, {'b'}, {'c'}, {'a','b'}, {'b','c'}, {'a','c'}, {'a','b','c'}

在python中

使用from itertools import *(因为那里的功能确实应该存在于默认名称空间中)，或者如果您愿意的话，请使用import itertools.

Use from itertools import * (since the functions there really should be in the default namespace), or import itertools if you'd like.

如果您关心排列:

permutations(yourString, 8)

如果您在意组合:

combinations(yourString, 8)

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其他语言

在其他语言中，可以使用简单的递归或迭代算法来生成这些算法.请参阅Wikipedia或stackoverflow.例如 http://en.wikipedia.org/wiki/Permutation#Systematic_generation_of_all_permutations

In other languages, there are simple recursive or iterative algorithms to generate these. See wikipedia or stackoverflow. e.g. http://en.wikipedia.org/wiki/Permutation#Systematic_generation_of_all_permutations

重要提示

请注意，排列数量为N!，例如，您的字符串将具有

Do note that the number of permutations is N!, so for example your string would have

• (69 choose 8) = 8 billion 组合的长度为8，因此...
长度为8的
• (69 choose 8) * 8! ~= 3.37 × 10^14 排列.

• (69 choose 8) = 8 billion combinations of length 8, and therefore...
• (69 choose 8) * 8! ~= 3.37 × 10^14 permutations of length 8.

如果要存储每个排列，则会用完内存.即使您不这样做(因为要减少它们)，也将花费很长时间才能运行，在现代计算机上可能需要1到10天.

You'll run out of memory if you are storing every permutation. Even if you don't (because you're reducing them), it'll take a long time to run, maybe somewhere between 1-10 days on a modern computer.

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