python使用數組作為索引遍歷數組

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python使用數組作為索引遍歷數組

import numpy as np

a=np.arange(0,5)
print(a)
# [0 1 2 3 4]
b=np.arange(0,10).reshape(5,2)
print(b)
# [[0 1]
#  [2 3]
#  [4 5]
#  [6 7]
#  [8 9]]

# 將一維數組作為二維數組的索引
c0=b[a][:,0]
print(c0)
# [0 2 4 6 8]
c1=b[a][:,1]
print(c1)
# [1 3 5 7 9]
c2=b[a][0]
print(c2)
# [0 1]
c3=b[a][4]
print(c3)
# [8 9]
c4=b[a][:4]
print(c4)
# [[0 1]
#  [2 3]
#  [4 5]
#  [6 7]]