Select date columns in python based on specific date criteria

Question

This is my sample code. My database contains columns for every date of the year, going back multiple years. Each column corresponds to a specific date.

import pandas as pd
df = pd.DataFrame([[10, 5, 25, 67,25,56], 
                   [20, 10, 26, 45, 56, 34], 
                   [30, 3, 27, 34, 78, 34], 
                   [40, 9, 28, 45, 34,76]], 
                  columns=[pd.to_datetime('2022-09-14'), pd.to_datetime('2022-08-14'), pd.to_datetime('2022-07-14'), pd.to_datetime('2021-09-14'),
                              pd.to_datetime('2020-09-14'), pd.to_datetime('2019-09-14')])

Is there a way to select only those columns which fit a particular criteria based on year, month or quarter.

For example, I was hoping to get only those columns which is the same date as today (any starting date) for every year. For example, today is Sep 14, 2022 and I need columns only for Sep 14, 2021, Sep 14, 2020 and so on. Another option could be to do the same on a month or quarter basis.
How can this be done in pandas?

Asked By: Green Finance

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Answer 1

Yes, you can do:

# day
df.loc[:, df.columns.day == 14]

   2022-09-14  2022-08-14  2022-07-14  2021-09-14  2020-09-14  2019-09-14
0          10           5          25          67          25          56
1          20          10          26          45          56          34
2          30           3          27          34          78          34
3          40           9          28          45          34          76


# month
df.loc[:, df.columns.month == 9]

   2022-09-14  2021-09-14  2020-09-14  2019-09-14
0          10          67          25          56
1          20          45          56          34
2          30          34          78          34
3          40          45          34          76


# quarter
df.loc[:, df.columns.quarter == 3]

   2022-09-14  2022-08-14  2022-07-14  2021-09-14  2020-09-14  2019-09-14
0          10           5          25          67          25          56
1          20          10          26          45          56          34
2          30           3          27          34          78          34
3          40           9          28          45          34          76

Answered By: Quang Hoang

Select date columns in python based on specific date criteria

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