import numpy as np
d=np.random.randn(4,4)
array([[ 1.16968447, -0.07650322, -0.30519481, -2.09278839],
[ 0.53350868, -0.8004209 , 0.38477468, 1.31876924],
[ 0.06461366, 0.82204993, 0.42034665, 0.30473843],
[ 1.13469745, -1.47969242, 2.36338208, -0.33700972]])
让我们过滤第二列中所有小于零的行:
d[:,1]<0
array([ True, True, False, True], dtype=bool)
您会看到,您得到了一个逻辑数组,您可以使用它来选择所需的行:
d[d[:,1]<0,:]
array([[ 1.16968447, -0.07650322, -0.30519481, -2.09278839],
[ 0.53350868, -0.8004209 , 0.38477468, 1.31876924],
[ 1.13469745, -1.47969242, 2.36338208, -0.33700972]])