How to take matrix input from the user and display the matrix in Python?

Question

I have an experience in java and c++ for 7 years now. I recently started learning python. Can someone please help me on how to read the input for the matrix and display the same in matrix format. This is the code I wrote:

import sys
# no of rows are equal to the number of columns.
n = int(input("Enter the number of rows in a matrix"))
a = [[0 for x in range (n)] for y in range(n)]
for i in range (n):
 for j in range(n):
 a[i][j]=int(input())
 print (a[i][j])
 print("\n")

• ividito: Possible duplicate of printing a two dimensional array in python

Answer 1

If you use pandas, and make a dataframe... if you enter 4 for the number of rows, and the numbers 1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16... the script below

import pandas as pd
n = int(input("Enter the number of rows in a matrix: "))
a = [[0] * n for i in range(n)]
col_names = []
row_names = []
for i in range(n):
 col_names.append('col ' + str(i+1))
 row_names.append('row ' + str(i+1)) 
 for j in range(n):
 a[i][j] = int(input())
print(pd.DataFrame(a,columns = col_names, index = row_names))

...will produce the following output.

 col 1 col 2 col 3 col 4
row 1 1 2 3 4
row 2 5 6 7 8
row 3 9 10 11 12
row 4 13 14 15 16

Another option... using numpy... and the same values from the first option...

import numpy as np
n = int(input("Enter the number of rows in a matrix: "))
a = [[0] * n for i in range(n)]
for i in range(n):
 for j in range(n):
 a[i][j] = int(input())
print(np.matrix(a))

...would produce

[[ 1 2 3 4]
 [ 5 6 7 8]
 [ 9 10 11 12]
 [13 14 15 16]]

Answer 2

 #program to print matirx by row and column input
a,b = map(int,input("Enter row and column of matrix separated by a space ").split())
# empty list for matrix 
m=[] 
# taking matrix input
for i in range(1,a+1):
 l=[]
 for j in range(1,b+1):
 n=int(input(f"Enter a[{i}][{j}] element "))
 l.append(n)
 m.append(l)
#printing in matrix form
for i in range(a):
 for j in range(b):
 if(j==b-1):
 print(m[i][j], end="")
 else:
 print(m[i][j], end=" ")
 if i!=a-1:
 print()

Answer 3

This example from a program I use for calculating bigger matrices:

matrix = []
rows = int(input("Num rows: "))
cols = int(input("Num columns: "))
for r in range(rows):
 row = []
 for c in range(cols):
 row.append(int(input("M1-> R: {} C: {}\n>>>".format(r+1, c+1))))
 matrix.append(row)
print(matrix)

This will work for non-square matrices as well. I also use Sympy for doing matrix calculations, but that's besides the point:)

Answer 4

print"ENter r and c"
r = int(input("Enter the number of rows in a matrix"))
c = int(input("Enter the number of columns in a matrix"))
a = [[int(input()) for x in range (c)] for y in range(r)]

Answer 5

import numpy as np
#Taking the number of rows and columns from user
n=int(input("Enter the number of Rows\n"))
m=int(input("Enter the number of Columns\n"))
"""
 You can either use this loop method for below list comprehension;
a=[]
for i in range(n):
 a.append([0] * m )
"""
#Creating a Empty matrix as as per the instruction of user;
a = [ [0] * m for i in range(n) ]
#Taking the element for a matrix from user;
for i in range (n):
 for j in range(m):
 print("Enter Element No:",i,j)
 a[i][j] = int(input())
print(np.matrix(a))

Answer 6

r = int(input("Enter Number of Rows : "))
c = int(input("Enter Number of Cols : "))
a = []
for i in range(r):
 b = []
 for j in range(c):
 j = int(input("Enter Number in pocket [" + str(i) + "][" + str(j) + "]"))
 b.append(j)
 a.append(b)
print("Matrix is ......")
for i in range(r):
 for j in range(c):
 print(a[i][j], end=" ")
 print()

Answer 7

r = int(input("Enter the number of rows in a matrix"))
c = int(input("Enter the number of columns in a matrix")) 
a = [list(map(int,input().split())) for _ in range(r)]
for i in a:
 print(*i)

Answer 8

list = []
for i in range(3):
 list.append([])
 for j in range(3):
 list[i].append(2)
 
for i in range(3):
 for j in range(3):
 print(list[i][j],end=" ")
 print()

• 4b0: It's good practice on StackOverflow to add an explanation as to why your solution should work.