Answers for "select columns 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

dataframe, groupby, select one

df.sort_values('date').groupby(['id', 'period', 'type']).first()