.mean()

The .mean() method produces a new Series or DataFrame with aggregate mean values for the groups in a GroupBy object.

Syntax

groupbyobject.mean(numeric_only)

numeric_only is a boolean value. True includes only int, float, and boolean columns. It defaults to True.

Example

The following example produces a GroupBy object from a DataFrame and executes the .mean() method on it.

import pandas as pd

df = pd.DataFrame({'Key' : ['A', 'A', 'A', 'B', 'B', 'C'],
                   'Value' : [15., 23., 17., 5., 8., 12.]})
print(df, end='\n\n')

group = df.groupby(['Key'], as_index=False)

print(group.mean())

This example produces the following output:

  Key  Value
0   A   15.0
1   A   23.0
2   A   17.0
3   B    5.0
4   B    8.0
5   C   12.0

  Key      Value
0   A  18.333333
1   B   6.500000
2   C  12.000000