python - 如何根据特定行中的值对 numpy 数组进行排序？

Question

我想知道如何才能根据其中一列中的值对整个数组进行排序。

我有:

array([5,2,8,2,4])

和:

array([[ 0,  1,  2,  3,  4],
       [ 5,  6,  7,  8,  9],
       [10, 11, 12, 13, 14],
       [15, 16, 17, 18, 19],
       [20, 21, 22, 23, 24]])

我想像这样将第一个数组附加到第二个数组:

array([[ 0,  1,  2,  3,  4],
       [ 5,  6,  7,  8,  9],
       [10, 11, 12, 13, 14],
       [15, 16, 17, 18, 19],
       [20, 21, 22, 23, 24],
       [5,  2,  8,  2,  4]])

然后按附加的行对数组进行排序以获得以下任一结果:

array([[1,  3,  4,  0,  2],
       [6,  8,  9,  5,  7],
       [11, 13, 14, 10, 12],
       [16, 18, 19, 15, 17],
       [21, 23, 24, 20, 22],
       [2,  2,  4,  5,  8]])

或者这个:

array([[ 2,  1,  3,  4,  0],
       [ 7,  6,  8,  9,  5],
       [12, 11, 13, 14, 10],
       [17, 16, 18, 19, 15],
       [22, 21, 23, 24, 20],
       [ 8,  5,  4,  2,  2]])

然后删除附加的列得到:

array([[1,  3,  4,  0,  2],
       [6,  8,  9,  5,  7],
       [11, 13, 14, 10, 12],
       [16, 18, 19, 15, 17],
       [21, 23, 24, 20, 22]])

或:

array([[ 2,  1,  3,  4,  0],
       [ 7,  6,  8,  9,  5],
       [12, 11, 13, 14, 10],
       [17, 16, 18, 19, 15],
       [22, 21, 23, 24, 20]])

是否有执行此过程的代码。我对 python 很陌生。非常感谢!

Answer 1

您可以使用 numpy.argsort获取包含数组排序索引的列表。然后，您可以使用它重新排列矩阵的列。

import numpy as np

c = np.array([5,2,8,2,4])    
a = np.array([[ 0,  1,  2,  3,  4],
              [ 5,  6,  7,  8,  9],
              [10, 11, 12, 13, 14],
              [15, 16, 17, 18, 19],
              [20, 21, 22, 23, 24]])

i = np.argsort(c)
a = a[:,i]