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implement isnull using full_like instead of zeros_like #7395

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Merged
merged 6 commits into from
Jan 23, 2024
Merged

implement isnull using full_like instead of zeros_like #7395

merged 6 commits into from
Jan 23, 2024

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@keewis
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@keewis keewis commented Dec 20, 2022

After changing the behavior of the implementation of *_like in pint, it seems comparisons fail now. As it turns out, this is because we're using zeros_like to return all-False arrays from isnull for input with non-nullable dtypes.

I'd argue that

full_like(data, dtype=bool, fill_value=False)

is a little bit easier to understand than

zeros_like(data, dtype=bool)

as the latter requires knowledge about the bit representation of False, so the change is not only to get pint to work properly.

  • Tests added

@github-actions github-actions bot added the topic-arrays related to flexible array support label Dec 20, 2022
@keewis
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keewis commented Dec 21, 2022

The test failures are real, unfortunately. pint's implementation of full_like explicitly defines the parameters, among them subok which the dask implementation does not support.

That means that update strategies might become tricky: the new version of pint would change the behavior and require us to implement isnull using full_like, but a bug in pint prevents that from working on dask. So not sure how to proceed?

One way might be to have pint issue a bugfix release first, wait on a release of xarray that contains this change, then release a version with the change in behavior (or deprecate / allow switching between the old / new behavior).

@dcherian
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dcherian commented Jan 15, 2023

So not sure how to proceed?

I think it'd be OK to have some compatibility code with hardcoded version numbers. It's simpler and more user-friendly than the other alternatives.

@keewis keewis mentioned this pull request Apr 14, 2023
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5 tasks
@dcherian dcherian added plan to merge Final call for comments and removed needs work labels Jan 18, 2024
@dcherian dcherian merged commit d34ebff into pydata:main Jan 23, 2024
@keewis keewis deleted the isnull-nonnullable branch January 28, 2024 14:19
andersy005 added a commit to TomNicholas/xarray that referenced this pull request Jan 30, 2024
@andersy005
Merge branch 'main' into namedarray-parallelcompat
53906e4 
* main: (153 commits)
  Add overloads to get_axis_num (pydata#8547)
  Fix CI: temporary pin pytest version to 7.4.* (pydata#8682)
  Bump the actions group with 1 update (pydata#8678)
  [namedarray] split `.set_dims()` into `.expand_dims()` and `broadcast_to()` (pydata#8380)
  Add chunk-friendly code path to `encode_cf_datetime` and `encode_cf_timedelta` (pydata#8575)
  Fix NetCDF4 C version detection (pydata#8675)
  groupby: Don't set `method` by default on flox>=0.9 (pydata#8657)
  Fix automatic broadcasting when wrapping array api class (pydata#8669)
  Fix unstack method when wrapping array api class (pydata#8668)
  Fix `variables` arg typo in `Dataset.sortby()` docstring (pydata#8670)
  dt.weekday_name - removal of function (pydata#8664)
  Add `dev` dependencies to `pyproject.toml` (pydata#8661)
  CI: Pin scientific-python/upload-nightly-action to release sha (pydata#8662)
  Update HOW_TO_RELEASE.md by clarifying where RTD build can be found (pydata#8655)
  ruff: use extend-exclude (pydata#8649)
  new whats-new section (pydata#8652)
  xfail another test on windows (pydata#8648)
  use first element of residual in _nonpolyfit_1d (pydata#8647)
  whatsnew for v2024.01.1
  implement `isnull` using `full_like` instead of `zeros_like` (pydata#7395)
  ...
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@keewis @dcherian @headtr1ck