import pandas as pd
df['created_at'] = pd.to_datetime(df['created_at'])
df['created_at'] = df['created_at'].dt.tz_localize('UTC').dt.tz_convert('Asia/Seoul')
df['cancelled_wait_time'] = df['cancelled_at'] - df['created_at']
df['year'] = df['created_at'].dt.year
df['month'] = df['created_at'].dt.month
df['day'] = df['created_at'].dt.day
df['date'] = df['created_at'].dt.date
df['time'] = df['created_at'].dt.time
df['quarter'] = df['created_at'].dt.quarter
df['weekday'] = df['created_at'].dt.weekday
df['hour'] = df['created_at'].dt.hour
df['created_at'] = pd.to_datetime(df['created_at']) + pd.DateOffset(hours=9)
df['created_at_30min'] = df['created_at'].dt.floor("30min")
df['created_at_hour'] = df['created_at'].dt.round("H")
pd.date_range(start='2018-01-01', end='2019-01-01', freq='1H')
DatetimeIndex(['2018-01-01 00:00:00', '2018-01-01 01:00:00', '2018-01-01 02:00:00', '2018-01-01 03:00:00', '2018-01-01 04:00:00', '2018-01-01 05:00:00', '2018-01-01 06:00:00', '2018-01-01 07:00:00', '2018-01-01 08:00:00', '2018-01-01 09:00:00', ... '2018-12-31 15:00:00', '2018-12-31 16:00:00', '2018-12-31 17:00:00', '2018-12-31 18:00:00', '2018-12-31 19:00:00', '2018-12-31 20:00:00', '2018-12-31 21:00:00', '2018-12-31 22:00:00', '2018-12-31 23:00:00', '2019-01-01 00:00:00'], dtype='datetime64[ns]', length=8761, freq='H')
pd.date_range(start='2018-01-01', end='2019-01-01', freq='1D')
DatetimeIndex(['2018-01-01', '2018-01-02', '2018-01-03', '2018-01-04', '2018-01-05', '2018-01-06', '2018-01-07', '2018-01-08', '2018-01-09', '2018-01-10', ... '2018-12-23', '2018-12-24', '2018-12-25', '2018-12-26', '2018-12-27', '2018-12-28', '2018-12-29', '2018-12-30', '2018-12-31', '2019-01-01'], dtype='datetime64[ns]', length=366, freq='D')
pd.date_range(start='2018-01-01', end='2019-01-01', freq='1D')[:-1]
DatetimeIndex(['2018-01-01', '2018-01-02', '2018-01-03', '2018-01-04', '2018-01-05', '2018-01-06', '2018-01-07', '2018-01-08', '2018-01-09', '2018-01-10', ... '2018-12-22', '2018-12-23', '2018-12-24', '2018-12-25', '2018-12-26', '2018-12-27', '2018-12-28', '2018-12-29', '2018-12-30', '2018-12-31'], dtype='datetime64[ns]', length=365, freq='D')