ENH: Return EAs from DataFrame reductions

[andrewgsavage]

Feature Type

• Adding new functionality to pandas

• Changing existing functionality in pandas

• Removing existing functionality in pandas

Problem Description

I'd like pandas to return an EA stored in a series when a reduction is applied to a DataFrame containing only that EA.

import pandas as pd
import pint_pandas

pd.DataFrame([[0, 1, 2]]).astype("pint[m]").sum()
0    0 meter
1    1 meter
2    2 meter
dtype: object

I would like this to return

0    0
1    1
2    2
dtype: pint[meter]

Feature Description

Store the reduction results in the same EA type as the EA values the reduction was called on.

Change https://github.com/pandas-dev/pandas/blob/main/pandas/core/internals/blocks.py#L345
to

res_values = type(self.values)([result])

Alternative Solutions

N/A

Additional Context

No response

[topper-123]

There is a PR in the works that will allow this, see #52788. There is one last API discussion still outstanding, but I think this has a good chance of being merged soon.

[jbrockmendel]

closed by #52788