沿给定轴改组NumPy数组 [英] Shuffling NumPy array along a given axis

问题描述

给出以下NumPy数组，

Given the following NumPy array,

> a = array([[1, 2, 3, 4, 5], [1, 2, 3, 4, 5],[1, 2, 3, 4, 5]])

它很简单，可以随机排列一行，

it's simple enough to shuffle a single row,

> shuffle(a[0])
> a
array([[4, 2, 1, 3, 5],[1, 2, 3, 4, 5],[1, 2, 3, 4, 5]])

是否可以使用索引符号独立地随机排列每一行?还是您必须遍历数组.我想到过类似的东西，

Is it possible to use indexing notation to shuffle each of the rows independently? Or do you have to iterate over the array. I had in mind something like,

> numpy.shuffle(a[:])
> a
array([[4, 2, 3, 5, 1],[3, 1, 4, 5, 2],[4, 2, 1, 3, 5]]) # Not the real output

尽管这显然行不通.

推荐答案

您必须多次调用numpy.random.shuffle()，因为您要分别改组多个序列. numpy.random.shuffle()适用于任何可变序列，实际上不是ufunc.分别洗排二维数组a的所有行的最短，最有效的代码可能是

You have to call numpy.random.shuffle() several times because you are shuffling several sequences independently. numpy.random.shuffle() works on any mutable sequence and is not actually a ufunc. The shortest and most efficient code to shuffle all rows of a two-dimensional array a separately probably is

map(numpy.random.shuffle, a)

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