# Python – Matrix Transpose

Contents

## Python – Matrix Transpose

In Python, a Matrix can be represented using a nested list. Lists inside the list are the rows.

Following is a simple example of nested list which could be considered as a 2x3 matrix.

``matrixA = [ [2, 8, 4], [3, 1, 5] ]``

The two lists inside matrixA are the rows of the matrix. Number of elements inside a row represent the number of columns.

Also, in Python programming, the indexing start from 0. So, when we specify matrixA in the program, that is actually [2+1][4+1] = , element of third row and fifth column.

In this tutorial, we will learn how to Transpose a Matrix in Python.

## Examples

### 1. Matrix Transpose using List Comprehension

In this example, we shall take a Matrix defined using Python List, and find its Transpose using List Comprehension.

Python Program

``````A = [ [2, 1, 3], [3, 1, 5] ]

# Transpose of A
B = [[A[j][i] for j in range(len(A))] for i in range(len(A))]

print(' A:', A)
print(' B:', B)``````
Run Code Copy

The code for addition of matrices using List Comprehension is very concise.

Output

`````` A: [[2, 1, 3], [3, 1, 5]]
B: [[2, 3], [1, 1], [3, 5]]``````

### 2. Matrix Transpose using For Loop

In this example, we shall take a matrix, represented using Python List and find its transpose by traversing through the elements using for Loop.

Python Program

``````A = [ [2, 1, 3], [3, 1, 5] ]

# Initialize B with size of A transpose
B = [[0 for j in range(len(A))] for i in range(len(A))]

for j in range(len(A)):
for i in range(len(A)):
B[i][j] = A[j][i]

print(' A:', A)
print(' B:', B)``````
Run Code Copy

Output

`````` A: [[2, 1, 3], [3, 1, 5]]
B: [[2, 3], [1, 1], [3, 5]]``````

This method is only for demonstrating the transpose of a matrix using for loop. List comprehension used in the first example is preferred, as it is concise.

## Summary

In this tutorial, we learned how to do Matrix Transpose in Python using For loop and List comprehension, with the help of well detailed examples.

## Related Tutorials

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