pydata / pydata/xarray

`pandas.MultiIndex` roundtrip with extension-arrays

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enhancement
Dominant language
Python
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Merged PRs (30d)
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Description

Is your feature request related to a problem?

In the following test

https://github.com/pydata/xarray/blob/85b5a160d1b143f5b7b7b9e8d4bc72e3beeea57d/xarray/tests/test_pandas_to_xarray.py#L159-L176

We encode that we expect extension arrays roundtripped with a MultiIndex as the dataframe index to be cast into numpy (broadcasting rules, if I remember correctly) but this should be relaxed to allow true roundtripping!

See https://github.com/pydata/xarray/pull/10559#discussion_r2239995709 for the originating discussion

Describe the solution you'd like

pandas.Dataframe with a MultiIndex and extension arrays in it should be roundtrippable without data type loss

Describe alternatives you've considered

N/A

Additional context

No response

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  4. Open a pull request that references the issue number.

Research direction

Start with the linked test in xarray/tests/test_pandas_to_xarray.py at lines 159-176 and read the originating discussion in pull request 10559. Update the roundtrip expectations so a pandas DataFrame with a MultiIndex and extension arrays preserves its data types, then run the targeted pandas-to-xarray tests.

Written by the indexing model from the issue text.

Assessment

Tech stack
pandas, python
Domain
data
Issue type
Feature
Difficulty
3/5
Estimated time
1-2 days
Activity status
Stale
Clarity
Mostly clear
Newbie friendliness
52/100

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