NumPy Matrix Subtraction

This tutorial will discuss the method to perform matrix subtraction operation in NumPy.

NumPy Matrix Subtraction With the - Operator

The infix subtraction operator - can be used to perform matrix subtraction in NumPy.

import numpy as np

matA = np.matrix([[1, 2, 3], [4, 5, 6], [7, 8, 9]])
matB = np.matrix([[9, 8, 7], [6, 5, 4], [3, 2, 1]])
matC = matA - matB
print(matC)

Output:

[[-8 -6 -4]
 [-2  0  2]
 [ 4  6  8]]

We subtracted the matrix matB from the matrix matB with the - operator in the above code. We first created the two matrices with the np.matrix() function. We then performed matrix subtraction and saved the result inside the matrix matC with matC = matA - matB.

We can also perform the same subtraction using 2D arrays with the np.array() instead of matrices. The following code example shows how to perform matrix subtraction using 2-dimensional arrays.

import numpy as np

matA = np.array([[1, 2, 3], [4, 5, 6], [7, 8, 9]])
matB = np.array([[9, 8, 7], [6, 5, 4], [3, 2, 1]])
matC = matA - matB
print(matC)

Output:

[[-8 -6 -4]
 [-2  0  2]
 [ 4  6  8]]

The above code gives the same result as the previous example because there is no difference in the - operator working with matrices and 2D arrays. It is because the np.matix is a subclass of np.ndarray.