# NumPy transpose()

Summary: in this tutorial, you’ll learn how to use the numpy `transpose()` function to reverse the axes of an array.

## Introduction to the numpy transpose() function

The numpy `transpose()` function reverses the axes of an array. Here’s the syntax of the `transpose()` function:

`numpy.transpose(a, axes=None)`

Code language: Python (python)

In this syntax:

• a is an input array. It can be a numpy array or any object that can be converted to a numpy array.
• axes is a tuple or a list that contains a permutation of [0,1,..,N-1] where N is the number of axes of the array a.

The `transpose()` function returns the array `a` with its axes permuted.

The `transpose()` function is equivalent to:

• `ndarray.T` property method that returns an array transposed.
• `ndarray.transpose(*axes)` method that returns an array transposed.

## NumPy transpose() function examples

Let’s take some examples of using the `transpose()` function.

### 1) Using transpose() function with 1-D array example

The following example uses the `transpose()` function with 1-D array:

`import numpy as np`

`a = np.array([1, 2, 3]) b = np.transpose(a) print(b)`

Code language: Python (python)

Output:

`[1 2 3]`

Code language: Python (python)

The `transpose()` function has no effect on a 1-D array because a transposed vector is simply the same vector.

### 2) Using numpy transpose() function with 2-D array example

The following example uses the `transpose()` function to transpose a 2-D array (or a matrix):

`import numpy as npa = np.array([ [1, 2, 3], [4, 5, 6] ])`

`b = np.transpose(a) print(b)`

Code language: Python (python)

Output:

`[[1 4] [2 5] [3 6]]`

Code language: Python (python)

In this example, the `transpose()` function transpose a (2,3) array. Basically, it swaps rows and columns of the array.

After the transposition, the first row of array a becomes the first column of the transposed array b, the second row of array a becomes the second column of the transposed array b.

## Summary

• Use the `transpose()` to transpose an array.