How to access specific rows in a pandas multiindex dataframe

Question

I'm working with what I think is a pandas multi-index data frame. Is there any way to make sure? My data looks like this.

            cinc           Outcome   
Side           1         2       1  2
WarNum                               
1       0.146344  0.029989       1  2
4       0.152565  0.056853       1  2
7       0.082757  0.017940       1  2
10      0.076032  0.022553       1  2
13      0.048538  0.005754       1  2

When I type in war_cinc.columns. I get the following output.

MultiIndex([(   'cinc', 1),
            (   'cinc', 2),
            ('Outcome', 1),
            ('Outcome', 2)],
           names=[None, 'Side'])

If I wanted to subset this data, how would I do so? (say I want to get the entire 2nd column of the cinc column of the dataframe)

Mayank Porwal · Accepted Answer · 2020-11-21 06:57:45Z

1

To check if your df has Multiindex, you can do this:

isinstance(war_cinc.index, pd.MultiIndex)

This will return True.

To check for hierarchical columns, you can check nlevels:

if len(war_cinc.columns.nlevels) > 1:

This will be True in your case.

You can get the entire 2nd column like:

war_cinc[(   'cinc', 2)]

You need to pass all levels of the column in a tuple to fetch the column values.

edited Nov 21, 2020 at 6:57

answered Nov 21, 2020 at 5:52

Mayank Porwal

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