(fix): pandas extension array repr for int64[pyarrow]

[ilan-gold]

Similar to #10315, we uncover more unexpected behavior with int64[pyarrow] as the testing data type.

• We were apparently relying on a call to np.array (via the xp.reshape) internally for the actual printing of the elements but this is not implemented for int64[pyarrow] (unlike other extension array types) and therefore broke without an explicit implementation. So we add that implementation

• Once this has been handled, the PandasExtensionArray is no longer being converted into a numpy array silently, and thus we need to ensure that the repr can handle the PandasExtensionArray natively.

• Lastly we add a KeyError to the lookup to ensure that this sort of thing cannot happen again.

• From (fix): no fill_value on reindex #10304

• Tests added

• User visible changes (including notable bug fixes) are documented in whats-new.rst

• New functions/methods are listed in api.rst

[ilan-gold]

Separately, I am not sure if max_width was meant to be inclusive or exclusive. The line length for the IntervalArray is exactly 100.

[ilan-gold]

Reverted the addition of IntervalArray a23de74 - see failure at https://github.com/pydata/xarray/actions/runs/15000671362/job/42146523169 for test_repr where the line length is exactly 100 instead of less than 100. I'm not clear what the behavior should be but let's keep this as minimal as possible. I will follow up with a more general "more test cases" PR.

[ilan-gold]

Is it possible these three tests are flaky? It seems to pass locally for me and on the face of it, has nothing to do with this PR>

[kmuehlbauer]

Is it possible these three tests are flaky? It seems to pass locally for me and on the face of it, has nothing to do with this PR>

@ilan-gold This surfaced with the release of dask 2025.5.0. Something has changed on the dask side and/or on the xarray side, which let the error surface.

Here is the stacktrace on my machine:

xarray/tests/test_backends.py:827 (TestDask.test_outer_indexing_reversed)
self = <xarray.tests.test_backends.TestDask object at 0x7f2da44c2ff0>

    def test_outer_indexing_reversed(self) -> None:
        # regression test for GH6560
        ds = xr.Dataset(
            {"z": (("t", "p", "y", "x"), np.ones((1, 1, 31, 40)))},
        )
    
        with self.roundtrip(ds) as on_disk:
>           subset = on_disk.isel(t=[0], p=0).z[:, ::10, ::10][:, ::-1, :]

/home/kai/python/projects/xarray/xarray/tests/test_backends.py:835: 
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ 
/home/kai/python/projects/xarray/xarray/core/dataset.py:2764: in isel
    var = var.isel(var_indexers)
/home/kai/python/projects/xarray/xarray/core/variable.py:1032: in isel
    return self[key]
/home/kai/python/projects/xarray/xarray/core/variable.py:782: in __getitem__
    return self._finalize_indexing_result(dims, data)
/home/kai/python/projects/xarray/xarray/core/variable.py:786: in _finalize_indexing_result
    return self._replace(dims=dims, data=data)
/home/kai/python/projects/xarray/xarray/core/variable.py:938: in _replace
    return type(self)(dims, data, attrs, encoding, fastpath=True)
/home/kai/python/projects/xarray/xarray/core/variable.py:365: in __init__
    super().__init__(
/home/kai/python/projects/xarray/xarray/namedarray/core.py:264: in __init__
    self._dims = self._parse_dimensions(dims)
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ 

self = <[AttributeError("'Variable' object has no attribute '_dims'") raised in repr()] Variable object at 0x7f2d5c6c6380>
dims = ('t', 'y', 'x')

    def _parse_dimensions(self, dims: _DimsLike) -> _Dims:
        dims = (dims,) if isinstance(dims, str) else tuple(dims)
        if len(dims) != self.ndim:
>           raise ValueError(
                f"dimensions {dims} must have the same length as the "
                f"number of data dimensions, ndim={self.ndim}"
            )
E           ValueError: dimensions ('t', 'y', 'x') must have the same length as the number of data dimensions, ndim=4

/home/kai/python/projects/xarray/xarray/namedarray/core.py:508: ValueError

[ilan-gold]

@kmuehlbauer Thanks for the heads up, sounds like I need to update my env then. Thanks for the info here!

[kmuehlbauer]

@kmuehlbauer Thanks for the heads up, sounds like I need to update my env then. Thanks for the info here!

See new issue #10321.

[dcherian]

Can we add __str__ to PandasExtensionArray instead?

[ilan-gold]

Could you clarify what you mean? The point here is to bypass PandasExtensionArray here because its __repr__ is PandasExtensionArray(array=[...]).

[dcherian]

OK right, can you add that statement as a comment please?