python random.shuffle的随机性 [英] python random.shuffle's randomness

问题描述

以下是来自python网站的关于

Following is from python website, about

random.shuffle(x[, random])

随机播放序列x.可选参数random是一个0参数的函数，返回[0.0, 1.0)中的一个随机浮点；默认情况下，这是功能random().

Shuffle the sequence x in place. The optional argument random is a 0-argument function returning a random float in [0.0, 1.0); by default, this is the function random().

请注意，即使len(x)很小，x的排列总数也比大多数随机数生成器的周期大；这意味着长序列的大多数排列永远不会生成.

Note that for even rather small len(x), the total number of permutations of x is larger than the period of most random number generators; this implies that most permutations of a long sequence can never be generated.

如果我想重复获得['a'..'k']的随机排列，似乎随机播放不会给我随机性.我的理解正确吗?

If I want to repeat getting a random permutation of ['a'..'k'], it seems shuffle will NOT give me the randomness. Is my understanding right?

谢谢！

推荐答案

对于长度为11的序列，有11个！或39,916,800(〜2 ^25.3 )可能的排列.对于 Merienne Twister (Python的随机算法)，周期为2 ¹⁹⁹³⁷ − 1.换句话说，您会没事的.

For a sequence of length 11, there are 11! or 39,916,800 (~ 2^25.3) possible permutations. For the Mersienne Twister (Python's random algorithm) the period is 2¹⁹⁹³⁷ − 1. In other words, you'll be fine.

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