Pandas – Sort DataFrame by Column

Pandas – Sort DataFrame by Column

To sort a DataFrame by a specific column in Python pandas, you can use pandas.DataFrame.sort_values() method. Call the sort_values() method on the DataFrame object, and pass the required column as string to the by named parameter.

dataframe.sort_values(by='column_name')

The sort_values() method does not modify the original DataFrame, but sorts the contents of given DataFrame in ascending order and returns a new sorted DataFrame.

You can sort the DataFrame in ascending or descending order by the specified column. To sort in descending order, specify ascending=False to the sort_values() method.

dataframe.sort_values(by='column_name', ascending=False)

In this tutorial, we shall go through some example programs, where we shall sort DataFrame by a specific column in ascending or descending order.

Examples

1. Sort DataFrame by specific column in ascending order

The default sorting order of sort_values() function is ascending order.

In this example, we shall take a DataFrame in df_1 with two columns: name and quantity. We have to sort the rows in the DataFrame by the column quantity, in ascending order.

1. Given a DataFrame in df_1 with two columns name and quantity.
2. Call sort_values() method on df_1, and pass the column name ‘quantity’ for the by named parameter.
3. The sort_values() method returns a new DataFrame with the contents of original DataFrame sorted in ascending order by the specified column.
4. Assign the returned value to a variable, say sorted_df, and print it to output.

import pandas as pd

# Take a DataFrame
df_1 = pd.DataFrame({
    'name': ['apple', 'banana', 'cherry', 'fig'],
    'quantity': [68, 74, 83, 45]
})

# Sort DataFrame by column
sorted_df = df_1.sort_values(by='quantity')
print(sorted_df)

Output

     name  quantity
3     fig        45
0   apple        68
1  banana        74
2  cherry        83

The rows of the DataFrame are sorted based on the increasing order of the specified column quantity.

2. Sort DataFrame by a column in descending order

To sort the dataframe in descending order a column, pass ascending=False argument to the sort_values() method.

In this example, we have to sort the DataFrame in df_1 in descending order by the column quantity.

1. Given a DataFrame in df_1 with two columns name and quantity.
2. Call sort_values() method on df_1, and pass the column name ‘quantity’ for the by named parameter, and False for the ascending named parameter.
3. The sort_values() method returns a new DataFrame with the contents of original DataFrame sorted in descending order by the specified column.
4. Assign the returned value to a variable, say sorted_df.

import pandas as pd

# Take a DataFrame
df_1 = pd.DataFrame({
    'name': ['apple', 'banana', 'cherry', 'fig'],
    'quantity': [68, 74, 83, 45]
})

# Sort DataFrame by column in descending order
sorted_df = df_1.sort_values(by='quantity', ascending=False)
print(sorted_df)

Output

     name  quantity
2  cherry        83
1  banana        74
0   apple        68
3     fig        45

The rows of the returned DataFrame are sorted in descending order by the column quantity.

Summary

In this Pandas Tutorial, we learned how to sort a DataFrame by a specific column in ascending or descending order, using sort_values() method of the DataFrame, with the help of well detailed Python example programs.