如何仅在 Python 中逐行打乱多维数组(所以不要打乱列)。

我正在寻找最有效的解决方案，因为我的矩阵非常庞大。是否也可以在原始数组上高效地执行此操作(以节省内存)？

例子:

import numpy as np
X = np.random.random((6, 2))
print(X)
Y = ???shuffle by row only not colls???
print(Y)

我现在期待的是原始矩阵:

[[ 0.48252164  0.12013048]
 [ 0.77254355  0.74382174]
 [ 0.45174186  0.8782033 ]
 [ 0.75623083  0.71763107]
 [ 0.26809253  0.75144034]
 [ 0.23442518  0.39031414]]

输出随机排列的行而不是列，例如:

[[ 0.45174186  0.8782033 ]
 [ 0.48252164  0.12013048]
 [ 0.77254355  0.74382174]
 [ 0.75623083  0.71763107]
 [ 0.23442518  0.39031414]
 [ 0.26809253  0.75144034]]

最佳答案

您可以使用 numpy.random.shuffle() .

This function only shuffles the array along the first axis of a multi-dimensional array. The order of sub-arrays is changed but their contents remains the same.

In [2]: import numpy as np                                                                                                                                                                                  

In [3]:                                                                                                                                                                                                     

In [3]: X = np.random.random((6, 2))                                                                                                                                                                        

In [4]: X                                                                                                                                                                                                   
Out[4]: 
array([[0.71935047, 0.25796155],
       [0.4621708 , 0.55140423],
       [0.22605866, 0.61581771],
       [0.47264172, 0.79307633],
       [0.22701656, 0.11927993],
       [0.20117207, 0.2754544 ]])

In [5]: np.random.shuffle(X)                                                                                                                                                                                

In [6]: X                                                                                                                                                                                                   
Out[6]: 
array([[0.71935047, 0.25796155],
       [0.47264172, 0.79307633],
       [0.4621708 , 0.55140423],
       [0.22701656, 0.11927993],
       [0.20117207, 0.2754544 ],
       [0.22605866, 0.61581771]])

对于其他功能，您还可以查看以下功能:

• random.Generator.shuffle

• random.Generator.permutation

• random.Generator.permuted

函数 random.Generator.permuted 在 Numpy 的 1.20.0 Release 中引入。

The new function differs from shuffle and permutation in that the subarrays indexed by an axis are permuted rather than the axis being treated as a separate 1-D array for every combination of the other indexes. For example, it is now possible to permute the rows or columns of a 2-D array.

关于python - Numpy shuffle 多维数组仅按行，保持列顺序不变，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/35646908/