Subtracting One Matirx From Another Using Numpy.ndarray With Example

Overview:

 

  • For subtracting one matrix from another matrix, the dimensions of both the matrices should be equal.

 

  • Subtraction of two matrices is similar to adding two matrices.

 

  • To subtract Matrix-B from Matrix-A, subtract each entry of Matrix-B from the corresponding entry of Matrix-A and place the result in the same position of the new matrix.

 

  • numpy.ndarray has __sub__() method which subtracts one ndarray object from another and returns the resultant ndarray object.

 

Example:

# import numpy module

import numpy as np

 

# import python standard library module - random

import random

 

# Function to populate a matrix with random data

def FillMatrix(matrix_in):

    for x in range(0, matrix_in.shape[0]):

        for y in range(0, matrix_in.shape[1]):

            matrix_in[x][y] = random.randrange(2, 10) + 2

 

# Create two 4x4 matrices using ndarray

matrix1 = np.ndarray((4,4))

matrix2 = np.ndarray((4,4))

 

# Fill the matrices i.e., the two dimensional arrays created using ndarray objects

FillMatrix(matrix1)

FillMatrix(matrix2)

 

# Add two matrices - two nd arrays

add_results = matrix1.__sub__(matrix2)

 

# Print Matrix1

print("Matrix1:")

print(matrix1)

 

# Print Matrix2

print("Matrix2:")

print(matrix2)

 

# Print the results of subtracting two matrices

print("Result of subtracting Matrix1 and Matrix2:")

print(add_results)

 

Output:

Matrix1:

[[  5.   9.   5.   8.]

 [  4.  10.  11.   9.]

 [  9.   5.   6.   5.]

 [ 10.  10.  10.   8.]]

Matrix2:

[[  9.  10.   9.   4.]

 [  9.   6.   8.   4.]

 [  9.  11.  11.   4.]

 [  6.   4.   8.  11.]]

Result of subtracting Matrix1 and Matrix2:

[[-4. -1. -4.  4.]

 [-5.  4.  3.  5.]

 [ 0. -6. -5.  1.]

 [ 4.  6.  2. -3.]]

 

 


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