How to sort an array by the nth column?

This recipe helps you sort an array by the nth column

Recipe Objective

While handling arrays, we might need to sort array on certain columns.

So this recipe is a short example on how to sort an array by the nth column. Let's get started.

Step 1 - Import the library


import numpy as np

Let's pause and look at these imports. Numpy is generally helpful in data manipulation while working with arrays. It also helps in performing mathematical operation.

Step 2 - Defining random array


a = np.array([[9, 2, 3],[4, 5, 6],[7, 0, 5]])

We have created a random array.

Step 3 - Sorting and printing array


a = a[a[:,1].argsort()] 
print(a)

We now use argsort feature to sort on any column. Here, we are sorting on 2nd column.

Step 4 - Lets look at our dataset now

Once we run the above code snippet, we will see:

Scroll down to the ipython file below to visualize the output.

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