Answers for "guide to groupby 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

Pandas groupby

>>> emp.groupby(['dept', 'gender']).agg({'salary':'mean'}).round(-3)