Python list sorted by row or column

Article reprint address (reposting it is also convenient for you to find when you use it later)
https://www.cnblogs.com/liyuxia713/p/7082091.html

If you want to sort by specifying a certain row or column, change it to the first row/last row, or the first column/last column to sort, and then switch it back

import numpy as np

>>> a
array([[ 2,  7,  4,  2],
       [35,  9,  1,  5],
       [22, 12,  3,  2]])
 
# 按最后一列顺序排序
>>> a[np.lexsort(a.T)]
array([[22, 12,  3,  2],
       [ 2,  7,  4,  2],
       [35,  9,  1,  5]])
 
# 按最后一列逆序排序
>>>a[np.lexsort(-a.T)]
array([[35,  9,  1,  5],
       [ 2,  7,  4,  2],
       [22, 12,  3,  2]])
 
# 按第一列顺序排序
>>> a[np.lexsort(a[:,::-1].T)]
array([[ 2,  7,  4,  2],
       [22, 12,  3,  2],
       [35,  9,  1,  5]])
 
# 按最后一行顺序排序
>>> a.T[np.lexsort(a)].T
array([[ 2,  4,  7,  2],
       [ 5,  1,  9, 35],
       [ 2,  3, 12, 22]])
 
按第一行顺序排序
>>> a.T[np.lexsort(a[::-1,:])].T
array([[ 2,  2,  4,  7],
       [ 5, 35,  1,  9],
       [ 2, 22,  3, 12]])