How to input element in 2d array

Question

Like below C++ Code, how could I use Python to input elements in 2d array? Please, help in writing the same program in Python3.

int main()
{
 int s = 3;
 int a[s][s];
 cout<<"Enter 9 Element in Square Matrix";
 for(int i =0;i<s;i++)
 {
  for(int j =0; j<s;j++)
  {
   cin>>a[i][j];
  }
 }
 cout<<"You Entered";
 for(int i =0;i<s;i++)
 {
  for(int j =0; j<s;j++)
  {
   cout<<a[i][j]<<"\t";
  }
 cout<<endl;
 }
return 0;
}
Output:
Enter 9 Elements in Square Matrix
1
2
3
4
5
6
7
8
9
You Entered: 
1 2 3
4 5 6
7 8 9

If there is a mistake in the program, please don't try to correct it. Thank you.

Can you post what you have tried so far in Python and where in the Python code you are having trouble please — johnashu
– johnashu, Commented Sep 21, 2017 at 15:07
Welcome to SO! Please take the tour and read minimal reproducible example. Please note that SO is not a code writing service. — Shawn Mehan
– Shawn Mehan, Commented Sep 21, 2017 at 15:12
Possible duplicate of How to input matrix (2D list) in Python? — Georgy
– Georgy, Commented Jul 12, 2019 at 9:33

Kaushik NP · Accepted Answer · 2017-09-21 15:26:20Z

4

Am gonna use list to store the 2D array here. There are many other structures you can use for storing a 2D array, but for basic needs, this will suffice.

n=int(input("Enter N for N x N matrix : "))         #3 here
l=[]                                                #use list for storing 2D array

#get the user input and store it in list (here IN : 1 to 9)
for i in range(n): 
  row_list=[]                                      #temporary list to store the row
  for j in range(n): 
     row_list.append(int(input()))                 #add the input to row list
  l.append(row_list)                               #add the row to the list

print(l)
# [[1, 2, 3], [4, 5, 6], [7, 8, 9]]

#Display the 2D array
for i in range(n):
  for j in range(n):
    print(l[i][j], end=" ")
  print()                                           #new line

'''
1 2 3 
4 5 6 
7 8 9 
'''

edited Sep 21, 2017 at 15:26

answered Sep 21, 2017 at 15:18

Kaushik NP

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2 Comments

Himanshu Rastogi Over a year ago

How to Print particular element by calling its index?

Kaushik NP Over a year ago

Sorry, didn't get you. You asking how to access data in the 2D list? If so, it is as you would do in C. Like here print(l[0][0]) will give 1

Snochacz · Accepted Answer · 2017-09-21 15:32:37Z

1

s = 3
a = [x[:] for x in [[0] * s] * s]

print("Enter 9 Element in Square Matrix")

for i in range(0, s):
    for j in range(0, s):
        a[i][j] = input()

print("You Entered")

for i in range(0, s):
    line = ''
    for j in range(0, s):
        line += a[i][j] + ' '
    print(line)

answered Sep 21, 2017 at 15:32

Snochacz

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2 Comments

Himanshu Rastogi Over a year ago

why you use 2 line?

Snochacz Over a year ago

Because print has built-in newline and I want to print all of them in the same line. Another way around is importing sys and using sys.stdout.write()

Martin Castro Alvarez · Accepted Answer · 2017-09-21 15:35:06Z

1

If you are not familiar with python, you should create a file called, for example, matrix.py and then add the following content:

matrix_size = 3
matrix = []

print("Enter {} Elements in Square Matrix:".format(matrix_size))
for i in range(0, matrix_size):
    row = []
    for j in range(0, matrix_size):
        row.append(input())
    matrix.append(row)

print("You entered:")
for i in range(0, matrix_size):
    print(" ".join(matrix[i]))

After saving the file, you can execute this file this way:

python3 matrix.py

Here is a sample output:

[martin@M7 tmp]$ python3 matrix.py
Enter 3 Elements in Square Matrix:
1
2
3
1
2
3
7
5
4
You entered:
1 2 3
1 2 3
7 5 4

answered Sep 21, 2017 at 15:35

Martin Castro Alvarez

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2 Comments

Himanshu Rastogi Over a year ago

Thanks, but why you put 0 in Range?

Martin Castro Alvarez Over a year ago

range(0, n) returns all the values in the following set: {0, 1, 2, ... n-1}. Arrays (and matrices) start at position 0. As a consequence, iterating in range(0, 9) will give you the values in {0, 1, 2, 3, 4, 5, 6, 7, 8} which account for the 9 position that you want to use in your example.

Shreya Saha · Accepted Answer · 2018-11-05 16:41:51Z

0

Say you want to create a 3*3 matrix:

Initialize the matrix as follows:

matrix = [x[:] for x in [[0] * 0] * 0]

Then take the matrix elements as input from the user:

    for i in range(0,3):
        row_list = []
        for j in range(0,3):
            row_list.append(int(input()))
        matrix.append(row_list)

answered Nov 5, 2018 at 16:41

Shreya Saha

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