在多索引中查询日期时间

Question

I have this dataframe (relevant here is the Multiindex):

 VAL FINT ID 2021-07-01 00:00:00 C7 32.0 C6 38.0 C5 94.0 2021-07-01 12:00:00 C7 28.0 C6 34.0 C5 95.0 2021-07-02 00:00:00 C7 29.0 C6 33.0 C5 22.1 2021-07-02 12:00:00 C7 29.0 C6 33.0 C5 62.2...

I want to create a new dataframe selecting data for hour at 12. I wanted to use query for this, but I don't know how to select the hour inside the query selection. I mean, I am searching something like

df.query('FINT.hour == 12')

which it doesn't work (while something like df.query('ID=="C7"') works well). I am using pandas 1.2.4. Thx.

Answer 1

For me working select level in MultiIndex like Series with .dt :

 df = df.query('FINT.dt.hour == 12') print (df) VAL FINT ID 2021-07-01 12:00:00 C7 28.0 C6 34.0 C5 95.0 2021-07-02 12:00:00 C7 29.0 C6 33.0 C5 62.2

With boolean indexing solution is:

 df[df.index.get_level_values('FINT').hour == 12]

Answer 2

You can also try getting datetime values from first level and use DatetimeIndex.indexer_at_time to get index locations of values at particular time of day.

 out = df.iloc[df.index.get_level_values(0).indexer_at_time('12:00')]

 print(out) VAL FINT ID 2021-07-01 12:00:00 C7 28.0 C6 34.0 C5 95.0 2021-07-02 12:00:00 C7 29.0 C6 33.0 C5 62.2