Adding Two Matrices Using Numpy.ndarray With Example

Adding two matrices - Two dimensional ndarray objects:

  • For adding two matrixes together both the matrices should have equal number of rows and columns.

 

  • To add two matrices corresponding elements of each matrix are added and placed in the same position in the resultant matrix.

 

  • The result of the matrix addition is a matrix of the same number of rows and columns.

 

  • ndarray of NumPy module supports matrix addition through the method __add__() which adds two ndarray objects of the same shape and returns the sum as another ndarray object.

 

Example:

# import numpy module

import numpy as np

 

# import python standard library module - random

import random

 

# Routine for printing a 2x2 matrix

def PrintMatrix(matrix_in):

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

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

            print("%d \t"%(matrix_in[x][y]), end='')

            if(y%3>1):

                print("\n")   

 

# Function to populate a 2x2 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 matrices using ndarray

matrix1 = np.ndarray((3,3))

matrix2 = np.ndarray((3,3))

 

# 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.__add__(matrix2)

 

# Print Matrix1

print("Matrix1:")

PrintMatrix(matrix1)

 

# Print Matrix2

print("Matrix2:")

PrintMatrix(matrix2)

 

# Print the results of adding two matrices

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

PrintMatrix(add_results)

 

 

Output:

Matrix1:

8   4   7  

 

7   9   7  

 

11 9   7  

 

Matrix2:

5   7   5  

 

7   11 10

 

9   11 5  

 

Result of adding Matrix1 and Matrix2:

13 11 12

 

14 20 17

 

20 20 12

 


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