DatetimeIndex reverse-lookup memo as I’m not quite sure

Introduction I almost always feel confused about pandas.DatetimeIndex when I set DatetimeIndex in pandas. More, I tend to drown in the sea of superabundant information, so I decided to make personal notes here. Click the table of contents to jump to the relevant item! For more details, please check official pandas website. Data used for case studies and versions of pandas and Python This post uses the following DataFrame as variable name “df”. First of all, let’s make sure the data type of index is DatetimeIndex. print(df.index) DatetimeIndex(['2020-01-02 03:04:05', '2021-06-07 08:09:10','2022-11-12 13:14:15'], dtype='datetime64[ns]', name='YMDHMS', freq=None) Good good. Then versions of pandas and Python are 0.24.2 and 3.7.2 respectively. * ‘Extract “day of the week” as a string; day_name ()’ was curried out in pandas 1.0.5 (added on June 26, 2020) しときます。 Well then, prepare in advance; import pandas as pd import datetime Case studies Confirming DataFrame configuration; index, columns, values and name print(df.index) #confirm index DatetimeIndex(['2020-01-02 03:04:05', '2021-06-07 08:09:10', '2022-11-12 13:14:15'], dtype='datetime64[ns]', name='YMDHMS', freq=None) print(df.columns) #confirm columns Index(['a', 'b', 'c'], dtype='object')df.values print( #confirm index name 'YMDHMS' print(df.values) #confirm values array([['a0', 'b0', 'c0'], ['a1', 'b1', 'c1'], ['a2', 'b2', 'c2']], dtype=object) print( # confirm column names None 指定した行番号のindex名を表示, index Print the index […]