Method swaplevel

pandas/core/series.py:4231–4322

Swap levels i and j in a :class:`MultiIndex`. Default is to swap the two innermost levels of the index. Parameters ---------- i, j : int or str Levels of the indices to be swapped. Can pass level name as string. copy : bool, default Fals

(
        self, i: Level = -2, j: Level = -1, copy: bool | lib.NoDefault = lib.no_default
    )

        return selectn.SelectNSeries(self, n=n, keep=keep).nsmallest()

    def swaplevel(
        self, i: Level = -2, j: Level = -1, copy: bool | lib.NoDefault = lib.no_default
    ) -> Series:
        """
        Swap levels i and j in a :class:`MultiIndex`.

        Default is to swap the two innermost levels of the index.

        Parameters
        ----------
        i, j : int or str
            Levels of the indices to be swapped. Can pass level name as string.
        copy : bool, default False
            This keyword is now ignored; changing its value will have no
            impact on the method.

            .. deprecated:: 3.0.0

                This keyword is ignored and will be removed in pandas 4.0. Since
                pandas 3.0, this method always returns a new object using a lazy
                copy mechanism that defers copies until necessary
                (Copy-on-Write). See the `user guide on Copy-on-Write
                <https://pandas.pydata.org/docs/dev/user_guide/copy_on_write.html>`__
                for more details.

        Returns
        -------
        Series
            Series with levels swapped in MultiIndex.

        See Also
        --------
        DataFrame.swaplevel : Swap levels i and j in a :class:`DataFrame`.
        Series.reorder_levels : Rearrange index levels using input order.
        MultiIndex.swaplevel : Swap levels i and j in a :class:`MultiIndex`.

        Examples
        --------
        >>> s = pd.Series(
        ...     ["A", "B", "A", "C"],
        ...     index=[
        ...         ["Final exam", "Final exam", "Coursework", "Coursework"],
        ...         ["History", "Geography", "History", "Geography"],
        ...         ["January", "February", "March", "April"],
        ...     ],
        ... )
        >>> s
        Final exam  History    January     A
                    Geography  February    B
        Coursework  History    March       A
                    Geography  April       C
        dtype: str

        In the following example, we will swap the levels of the indices.
        Here, we will swap the levels column-wise, but levels can be swapped row-wise
        in a similar manner. Note that column-wise is the default behavior.
        By not supplying any arguments for i and j, we swap the last and second to
        last indices.