Answers for "groupby in a dataframe pandas"

group by pandas examples

>>> n_by_state = df.groupby("state")["state"].count()
>>> n_by_state.head(10)
state
AK     16
AL    206
AR    117
AS      2
AZ     48
CA    361
CO     90
CT    240
DC      2
DE     97
Name: last_name, dtype: int64

groupby

df['frequency'] = df['county'].map(df['county'].value_counts())

    county  frequency
1   N       5
2   N       5
3   C       1
4   N       5
5   S       1
6   N       5
7   N       5

groupy pandas

python groupby