bad conda solve with pandas 2

[dcherian]

What happened?

Pandas 2 is out.

We have a pandas<2 pin for our latest release, but mamba is now returning xarray=2023.1.0 and pandas=2.0 which is making cf-xarray and flox tests fail.

It looks like any project that tests resample without pinning pandas will fail.

I opened the issue here for visibility. It seems we might need a repodata patch to disallow pandas<2?

cc @ocefpaf

What did you expect to happen?

No response

Minimal Complete Verifiable Example

No response

MVCE confirmation

• Minimal example — the example is as focused as reasonably possible to demonstrate the underlying issue in xarray.
• Complete example — the example is self-contained, including all data and the text of any traceback.
• Verifiable example — the example copy & pastes into an IPython prompt or Binder notebook, returning the result.
• New issue — a search of GitHub Issues suggests this is not a duplicate.

Relevant log output

No response

Anything else we need to know?

No response

Environment

[ocefpaf]

We need to do a repodata patch for the current xarray. I'll get to it soon.

[ocefpaf]

@dcherian do you mind taking a look at conda-forge/conda-forge-repodata-patches-feedstock#426? Please check the versions patched and the applied patch! Thanks!

[rabernat]

Do we have a plan to support pandas 2?

[keewis]

with the merge of #7441 we should already support pandas=2.0 on main. I think we can try unpinning in a PR to see how many of the errors from #7707 are related to pandas (none, hopefully, but I'm not sure).

[spencerkclark]

The cftime-related ones are still pandas related, but hopefully should be straightforward to address.

[keewis]

CI says these are the tests we'd need to fix:

FAILED xarray/tests/test_coding_times.py::test_should_cftime_be_used_source_outside_range - Failed: DID NOT RAISE <class 'ValueError'>
FAILED xarray/tests/test_cftimeindex.py::test_to_datetimeindex_out_of_range[360_day] - Failed: DID NOT RAISE <class 'ValueError'>
FAILED xarray/tests/test_cftimeindex.py::test_to_datetimeindex_out_of_range[365_day] - Failed: DID NOT RAISE <class 'ValueError'>
FAILED xarray/tests/test_cftimeindex.py::test_to_datetimeindex_out_of_range[366_day] - Failed: DID NOT RAISE <class 'ValueError'>
FAILED xarray/tests/test_cftimeindex.py::test_to_datetimeindex_out_of_range[all_leap] - Failed: DID NOT RAISE <class 'ValueError'>
FAILED xarray/tests/test_cftimeindex.py::test_to_datetimeindex_out_of_range[gregorian] - Failed: DID NOT RAISE <class 'ValueError'>
FAILED xarray/tests/test_cftimeindex.py::test_to_datetimeindex_out_of_range[julian] - Failed: DID NOT RAISE <class 'ValueError'>
FAILED xarray/tests/test_cftimeindex.py::test_to_datetimeindex_out_of_range[noleap] - Failed: DID NOT RAISE <class 'ValueError'>
FAILED xarray/tests/test_cftimeindex.py::test_to_datetimeindex_out_of_range[proleptic_gregorian] - Failed: DID NOT RAISE <class 'ValueError'>
FAILED xarray/tests/test_cftimeindex.py::test_to_datetimeindex_out_of_range[standard] - Failed: DID NOT RAISE <class 'ValueError'>
FAILED xarray/tests/test_dataarray.py::TestDataArray::test_sel_float - NotImplementedError: float16 indexes are not supported

Edit: one more on windows:

FAILED xarray/tests/test_utils.py::test_maybe_coerce_to_str[1-2-expected1] - AssertionError: assert dtype('int64') == dtype('int32')
 +  where dtype('int64') = Index([1, 2], dtype='int64').dtype
 +  and   dtype('int32') = Index([1, 2], dtype='int32').dtype

Edit2: the doctests also fail:

FAILED xarray/core/accessor_dt.py::xarray.core.accessor_dt.DatetimeAccessor
FAILED xarray/core/accessor_dt.py::xarray.core.accessor_dt.TimedeltaAccessor
FAILED xarray/core/dataarray.py::xarray.core.dataarray.DataArray.groupby

[CommonClimate]

Eagerly awaiting a resolution to this, as the newest Pyleoclim release will be requiring pandas >=2.0, which will make it incompatible with xarray as things stand.

[mroeschke]

CI says these are the tests we'd need to fix:

Chiming in from the pandas side on those failures, I think they are all expected https://pandas.pydata.org/docs/whatsnew/v2.0.0.html namely

• Since pandas supports s, ms and us numpy datetime resolutions now, I'm guessing that's why test_to_datetimeindex_out_of_range and test_should_cftime_be_used_source_outside_range are failing
• For test_sel_float, pd.Index intentionally does not support np.float16 as dtype anymore (we never had an indexing engine for this dtype)
• For test_maybe_coerce_to_str, this might be expected too as Index dtypes can hold np.int32 types now

[jsignell]

In that case it could be reasonable to mimic the pattern in test_groupby and mark the failing tests with a @pytest.mark.skipif(not has_pandas_version_two, reason="Tests a scenario that only raises when pandas <= 2")

[dcherian]

I think they are all expected pandas.pydata.org/docs/whatsnew/v2.0.0.html namely

Yes they are. We just haven't had the time to fix things.

[keewis]

For test_should_cftime_be_used_source_outside_range and test_to_datetimeindex_out_of_range I'd probably use a date that is outside the s resolution range (not sure if that actually makes sense, though). What do you think, @spencerkclark?

For test_maybe_coerce_to_str I think the reason is that we use np.array to cast a python int to an array, but the default resolution is different on windows. Apparently, pandas still uses int64 if constructed directly from python ints, but numpy uses int32 on windows, and as you say pandas does not insist on int64 anymore. The fix would be to explicitly specify the dtype in the array calls.

And finally, I'm not sure what to do with test_sel_float. Maybe we can split the monolithic test into one parametrized by dtype and skip the float16 test variant for pandas>=2.0?