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]