Numpy的索引筛选

import numpy as np

A = np.arange(3,15).reshape(3,4)
print(A)
print(A[2])
print(A[2,:])
print(A[:,1])
print(A[2,1])
print(A[2][1])
print(A[1,1:3])

for row in A:
    print(row)   #迭代每一行

for column in A.T:
    print(column)   #迭代每一列

print(a.flatten())  #转为一维数组
print(a.flat)

for item in A.flat:
    print(item)   #迭代每一个元素