pandas.Series.swaplevel — pandas 2.2.3 documentation (original) (raw)

Series.swaplevel(i=-2, j=-1, copy=None)[source]#

Swap levels i and j in a MultiIndex.

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

Parameters:

i, jint or str

Levels of the indices to be swapped. Can pass level name as string.

copybool, default True

Whether to copy underlying data.

Note

The copy keyword will change behavior in pandas 3.0.Copy-on-Writewill be enabled by default, which means that all methods with acopy keyword will use a lazy copy mechanism to defer the copy and ignore the copy keyword. The copy keyword will be removed in a future version of pandas.

You can already get the future behavior and improvements through enabling copy on write pd.options.mode.copy_on_write = True

Returns:

Series

Series with levels swapped in 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: object

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 behaviour. By not supplying any arguments for i and j, we swap the last and second to last indices.

s.swaplevel() Final exam January History A February Geography B Coursework March History A April Geography C dtype: object

By supplying one argument, we can choose which index to swap the last index with. We can for example swap the first index with the last one as follows.

s.swaplevel(0) January History Final exam A February Geography Final exam B March History Coursework A April Geography Coursework C dtype: object

We can also define explicitly which indices we want to swap by supplying values for both i and j. Here, we for example swap the first and second indices.

s.swaplevel(0, 1) History Final exam January A Geography Final exam February B History Coursework March A Geography Coursework April C dtype: object