Question

I need help writing a program in python that reads from a file and performs matrix multiplication. the file has this format

1 
4 
2 
1 1 1 1
1 1
2 2
3 3
4 4

which means :

1  #rows in A
4  #cols in A, rows in B
2  #cols in B

Matrix A contents:
 1 1 1 1

Matrix B contents:
 1 1
 2 2
 3 3
 4 4

i need to be able to read in the file, and then multiply the two matrices and print out the result .. thanks

Answer 1

SOURCE CODE:

*Please follow the comments to better understand the code.

**Please look at the Screenshot below and use this code to copy-paste.

***The code in the below screenshot is neatly indented for better understanding.


# function to print the matrix
def print_matrix(matrix, rows, cols):
    for i in range(rows):
        for j in range(cols):
            print(matrix[i][j], end=' ')
        print()


# open file
file_name = input("Enter the file name: ")
with open(file_name) as file:
    # read data from file
    data = file.readlines()

    # read the columns and rows
    rows_a = int(data[0])
    col_a_row_b = int(data[1])
    cols_b = int(data[2])

    # Read contents of matrix a
    matrix_a = []
    for i in range(rows_a):
        # read each row and append it to matrix
        row = [int(x) for x in data[3 + i].split()]
        matrix_a.append(row)
    # Read contents of matrix b
    matrix_b = []
    for i in range(col_a_row_b):
        # read each row and append it to matrix
        row = [int(x) for x in data[3 + i + rows_a].split()]
        matrix_b.append(row)

    # print the matrices
    print('Matrix A contents:')
    print_matrix(matrix_a, rows_a, col_a_row_b)
    print('Matrix B contents:')
    print_matrix(matrix_b, col_a_row_b, cols_b)

    # take an empty list
    res = []
    # perform the multiplication
    for i in range(rows_a):
        row = []
        for j in range(cols_b):
            s = 0
            for k in range(col_a_row_b):
                # resulted sum
                s += matrix_a[i][k] * matrix_b[k][j]
            row.append(s)
        # append the row to result
        res.append(row)

    print("\nThe result is:")
    print_matrix(res, rows_a, cols_b)

========

OUTPUT