Matrix is nothing but a rectangular arrangement of data or numbers. In other words, it is a rectangular array of data or numbers. The horizontal entries in a matrix are called as ‘rows’ while the vertical entries are called as ‘columns’. If a matrix has r number of rows and c number of columns then the order of matrix is given by r x c. Each entries in a matrix can be integer values, or floating values, or even it can be complex numbers.
Examples:
// 3 x 4 matrix
1 2 3 4
M = 4 5 6 7
6 7 8 9
// 2 x 3 matrix in Python
A = ( [ 2, 5, 7 ],
[ 4, 7, 9 ] )
// 3 x 4 matrix in Python where entries are floating numbers
B = ( [ 1.0, 3.5, 5.4, 7.9 ],
[ 9.0, 2.5, 4.2, 3.6 ],
[ 1.5, 3.2, 1.6, 6.5 ] )
In Python, we can take a user input matrix in different ways. Some of the methods for user input matrix in Python are shown below:
Code #1:
Python3
# A basic code for matrix input from userR = int(input("Enter the number of rows:"))C = int(input("Enter the number of columns:"))# Initialize matrixmatrix = []print("Enter the entries rowwise:")# For user inputfor i in range(R): # A for loop for row entries a =[] for j in range(C): # A for loop for column entries a.append(int(input())) matrix.append(a)# For printing the matrixfor i in range(R): for j in range(C): print(matrix[i][j], end = " ") print() |
Output:
Enter the number of rows:2 Enter the number of columns:3 Enter the entries rowwise: 1 2 3 4 5 6 1 2 3 4 5 6
Time complexity: O(RC)
Auxiliary space: O(RC)
One liner:
Python3
# one-liner logic to take input for rows and columnsmat = [[int(input()) for x in range (C)] for y in range(R)] |
Code #2: Using map() function and Numpy. In Python, there exists a popular library called NumPy. This library is a fundamental library for any scientific computation. It is also used for multidimensional arrays and as we know matrix is a rectangular array, we will use this library for user input matrix.
Python3
import numpy as npR = int(input("Enter the number of rows:"))C = int(input("Enter the number of columns:"))print("Enter the entries in a single line (separated by space): ")# User input of entries in a # single line separated by spaceentries = list(map(int, input().split()))# For printing the matrixmatrix = np.array(entries).reshape(R, C)print(matrix) |
Output:
Enter the number of rows:2 Enter the number of columns:2 Enter the entries in a single line separated by space: 1 2 3 1 [[1 2] [3 1]]
Time complexity: O(RC), as the code iterates through RC elements to create the matrix.
Auxiliary space: O(RC), as the code creates an RC sized matrix to store the entries.
