13: Numpy and Broadcasting

import numpy as np

A = np.ones((2, 3))
B = 3
print(A+B) # result 1

[[4. 4. 4.]
 [4. 4. 4.]]

B = np.ones((2, 1))
B

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

A = np.ones((2, 3))
B = np.ones((2, 1)) # B has one column
print(A+B) # result 2

[[2. 2. 2.]
 [2. 2. 2.]]

A = np.ones((2, 3))
B = np.ones((1, 3))
print(A+B) # result 3

[[2. 2. 2.]
 [2. 2. 2.]]