How to Sort an Index in Pandas DataFrame

You can sort an index in Pandas DataFrame:

(1) In an ascending order:

df = df.sort_index()

(2) In a descending order:

df = df.sort_index(ascending=False)

Let’s see how to sort an index by reviewing an example.

The Example

To start, let’s create a simple DataFrame:

import pandas as pd

data = {'Product': ['Computer','Printer','Monitor','Desk','Phone','Tablet','Scanner'],
          'Price': [1100,150,500,350,100,300,120]
        }

df = pd.DataFrame(data, columns = ['Product','Price'])

print(df)

By default, the index is sorted in an ascending order:

Let’s replace the default index values with the following unsorted values:

index = ['Item_D','Item_B','Item_A','Item_C','Item_F','Item_G','Item_E']

The goal is to sort the above values in an ascending order.

The current DataFrame with the new unsorted index is as follows:

import pandas as pd

data = {'Product': ['Computer','Printer','Monitor','Desk','Phone','Tablet','Scanner'],
          'Price': [1100,150,500,350,100,300,120]
        }

df = pd.DataFrame(data, columns = ['Product','Price'], index = ['Item_D','Item_B','Item_A','Item_C','Item_F','Item_G','Item_E'])

print(df)

As you can see, the current index values are unsorted:

Sort the Index in an Ascending Order in Pandas DataFrame

In order to sort the index in an ascending order, you’ll need to add the following syntax to the code:

df = df.sort_index()

So the complete Python code to sort the index is:

import pandas as pd

data = {'Product': ['Computer','Printer','Monitor','Desk','Phone','Tablet','Scanner'],
          'Price': [1100,150,500,350,100,300,120]
        }

df = pd.DataFrame(data, columns = ['Product','Price'], index = ['Item_D','Item_B','Item_A','Item_C','Item_F','Item_G','Item_E'])

df = df.sort_index()

print(df)

Notice that the index is now sorted in an ascending order:

Sort the Index in a Descending Order in Pandas DataFrame

What if you’d like to sort the index in a descending order?

In that case, you’ll need to add the following syntax:

df = df.sort_index(ascending=False)

Here is the complete Python code:

import pandas as pd

data = {'Product': ['Computer','Printer','Monitor','Desk','Phone','Tablet','Scanner'],
          'Price': [1100,150,500,350,100,300,120]
        }

df = pd.DataFrame(data, columns = ['Product','Price'], index = ['Item_D','Item_B','Item_A','Item_C','Item_F','Item_G','Item_E'])

df = df.sort_index(ascending=False)

print(df)

You’ll now see that the index is sorted in a descending order:

Index is Numeric

So far, the index sorted was non-numeric.

The same concept would apply if the index values are numeric:

index = [400,200,100,300,600,700,500]

Let’s sort the index in an ascending order:

import pandas as pd

data = {'Product': ['Computer','Printer','Monitor','Desk','Phone','Tablet','Scanner'],
          'Price': [1100,150,500,350,100,300,120]
        }

df = pd.DataFrame(data, columns = ['Product','Price'], index = [400,200,100,300,600,700,500])

df = df.sort_index()

print(df)

The index will be sorted as follows:

You may visit the Pandas Documentation to learn more about df.sort_index.