How to sort a Pandas DataFrame by index?

Question

When there is an DataFrame like the following:

import pandas as pd
df = pd.DataFrame([1, 1, 1, 1, 1], index=[100, 29, 234, 1, 150], columns=['A'])

How can I sort this dataframe by index with each combination of index and column value intact?

Answer 1

Dataframes have a sort_index method which returns a copy by default. Pass inplace=True to operate in place.

import pandas as pd
df = pd.DataFrame([1, 2, 3, 4, 5], index=[100, 29, 234, 1, 150], columns=['A'])
df.sort_index(inplace=True)
print(df.to_string())

Gives me:

     A
1    4
29   2
100  1
150  5
234  3

Answer 2

Slightly more compact:

df = pd.DataFrame([1, 2, 3, 4, 5], index=[100, 29, 234, 1, 150], columns=['A'])
df = df.sort_index()
print(df)

Note:

• sort has been deprecated, replaced by sort_index for this scenario
• preferable not to use inplace as it is usually harder to read and prevents chaining. See explanation in answer here: Pandas: peculiar performance drop for inplace rename after dropna