如何将数组添加到矩阵的列中？ （蟒蛇麻木）

Question

Like this:

import numpy as np
a = np.zeros((3,3))
b = np.ones((3,1))
a[:,2] += b

expected:

a = 
0,0,1
0,0,1
0,0,1

in fact:

ValueError: non-broadcastable output operand with shape (3,) doesn't match the broadcast shape (3,3)

What should I do?

Answer 1

Specifying the range of column is required

eg a[:,0:1] for column 0, a[:,1:2] for column 1, and a[:,2:] for column 2.

import numpy as np
a = np.zeros((3,3))
b = np.ones((3,1))
a[:,2:] += b

output:

 array([[0., 0., 1.], [0., 0., 1.], [0., 0., 1.]])