pandas.MultiIndex.remove_unused_levels#

MultiIndex.remove_unused_levels()[source]#

Create new MultiIndex from current that removes unused levels.

Unused level(s) means levels that are not expressed in the labels. The resulting MultiIndex will have the same outward appearance, meaning the same .values and ordering. It will also be .equals() to the original.

Returns

MultiIndex

Examples

>>> mi = pd.MultiIndex.from_product([range(2), list('ab')])
>>> mi
MultiIndex([(0, 'a'),
            (0, 'b'),
            (1, 'a'),
            (1, 'b')],
           )

>>> mi[2:]
MultiIndex([(1, 'a'),
            (1, 'b')],
           )

The 0 from the first level is not represented and can be removed

>>> mi2 = mi[2:].remove_unused_levels()
>>> mi2.levels
FrozenList([[1], ['a', 'b']])