详解python中[-1]、[:-1]、[::-1]、[n::-1]使用方法

import numpy as np
a=np.random.rand(5)
print(a)
[ 0.64061262 0.8451399  0.965673  0.89256687 0.48518743]
 
print(a[-1]) ###取最后一个元素
[0.48518743]
 
print(a[:-1]) ### 除了最后一个取全部
[ 0.64061262 0.8451399  0.965673  0.89256687]
 
print(a[::-1]) ### 取从后向前（相反）的元素
[ 0.48518743 0.89256687 0.965673  0.8451399  0.64061262]
 
print(a[2::-1]) ### 取从下标为2的元素翻转读取
[ 0.965673 0.8451399  0.64061262]

a = np.array([[0, 1, 2, 3, 4], [5, 6, 7, 8, 9]])
b = a[::-1, :]
print(b)
 
[[5 6 7 8 9]
 [0 1 2 3 4]]