issues

I haven't looked at this too closely but it appears that this is a way to save MultiIndexed datasets to netCDF. So we may be able to do sparse -> multiindex -> netCDF

http://cfconventions.org/Data/cf-conventions/cf-conventions-1.8/cf-conventions.html#compression-by-gathering

cc @fujiisoup

What is your issue?

Here's the output from the Scientific Python Repo Review tool.

There's an online version here.

On mac I run pipx run 'sp-repo-review[cli]' --format html --show err gh:pydata/xarray@main | pbcopy

A lot of these seem fairly easy to fix. I'll note that there's a large number of mypy config suggestions.

General

• Detected build backend: setuptools.build_meta
• Detected license(s): Apache Software License

<table> <tr><th>?</th><th>Name</th><th>Description</th></tr> <tr style="color: red;"> <td>❌</td> <td>PY007</td> <td> Supports an easy task runner (nox or tox)

Projects must have a noxfile.py or tox.ini to encourage new contributors.

</td> </tr> </table>

PyProject

See https://github.com/pydata/xarray/issues/8239#issuecomment-1739363809

<table> <tr><th>?</th><th>Name</th><th>Description</th></tr> <tr style="color: red;"> <td>❌</td> <td>PP305</td> <td> Specifies xfail_strict

xfail_strict should be set. You can manually specify if a check should be strict when setting each xfail.

[tool.pytest.ini_options]
xfail_strict = true

</td> </tr> <tr style="color: red;"> <td>❌</td> <td>PP308</td> <td> Specifies useful pytest summary

-ra should be in addopts = [...] (print summary of all fails/errors).

[tool.pytest.ini_options]
addops = ["-ra", "--strict-config", "--strict-markers"]

</td> </tr> </table>

Pre-commit

<table> <tr><th>?</th><th>Name</th><th>Description</th></tr> <tr style="color: red;"> <td>❌</td> <td>PC110</td> <td> Uses black

Use https://github.com/psf/black-pre-commit-mirror instead of https://github.com/psf/black in .pre-commit-config.yaml

</td> </tr> <tr style="color: red;"> <td>❌</td> <td>PC160</td> <td> Uses codespell

Must have https://github.com/codespell-project/codespell repo in .pre-commit-config.yaml

</td> </tr> <tr style="color: red;"> <td>❌</td> <td>PC170</td> <td> Uses PyGrep hooks (only needed if RST present)

Must have https://github.com/pre-commit/pygrep-hooks repo in .pre-commit-config.yaml

</td> </tr> <tr style="color: red;"> <td>❌</td> <td>PC180</td> <td> Uses prettier

Must have https://github.com/pre-commit/mirrors-prettier repo in .pre-commit-config.yaml

</td> </tr> <tr style="color: red;"> <td>❌</td> <td>PC191</td> <td> Ruff show fixes if fixes enabled

If --fix is present, --show-fixes must be too.

</td> </tr> <tr style="color: red;"> <td>❌</td> <td>PC901</td> <td> Custom pre-commit CI message

Should have something like this in .pre-commit-config.yaml:

ci:
  autoupdate_commit_msg: 'chore: update pre-commit hooks'

</td> </tr> </table>

MyPy

<table> <tr><th>?</th><th>Name</th><th>Description</th></tr> <tr style="color: red;"> <td>❌</td> <td>MY101</td> <td> MyPy strict mode

Must have strict in the mypy config. MyPy is best with strict or nearly strict configuration. If you are happy with the strictness of your settings already, ignore this check or set strict = false explicitly.

[tool.mypy]
strict = true

</td> </tr> <tr style="color: red;"> <td>❌</td> <td>MY103</td> <td> MyPy warn unreachable

Must have warn_unreachable = true to pass this check. There are occasionally false positives (often due to platform or Python version static checks), so it's okay to ignore this check. But try it first - it can catch real bugs too.

[tool.mypy]
warn_unreachable = true

</td> </tr> <tr style="color: red;"> <td>❌</td> <td>MY104</td> <td> MyPy enables ignore-without-code

Must have "ignore-without-code" in enable_error_code = [...]. This will force all skips in your project to include the error code, which makes them more readable, and avoids skipping something unintended.

[tool.mypy]
enable_error_code = ["ignore-without-code", "redundant-expr", "truthy-bool"]

</td> </tr> <tr style="color: red;"> <td>❌</td> <td>MY105</td> <td> MyPy enables redundant-expr

Must have "redundant-expr" in enable_error_code = [...]. This helps catch useless lines of code, like checking the same condition twice.

[tool.mypy]
enable_error_code = ["ignore-without-code", "redundant-expr", "truthy-bool"]

</td> </tr> <tr style="color: red;"> <td>❌</td> <td>MY106</td> <td> MyPy enables truthy-bool

Must have "truthy-bool" in enable_error_code = []. This catches mistakes in using a value as truthy if it cannot be falsey.

[tool.mypy]
enable_error_code = ["ignore-without-code", "redundant-expr", "truthy-bool"]

</td> </tr> </table>

Ruff

<table> <tr><th>?</th><th>Name</th><th>Description</th></tr> <tr style="color: red;"> <td>❌</td> <td>RF101</td> <td> Bugbear must be selected

Must select the flake8-bugbear B checks. Recommended:

[tool.ruff]
select = [
  "B",  # flake8-bugbear
]

</td> </tr> </table>

• [x] Tests added
• [x] Passes black . && mypy . && flake8
• [ ] Fully documented, including whats-new.rst for all changes and api.rst for new API

This adds plotting methods to GroupBy objects so that it's easy to plot each group as a facet. I'm finding this super helpful in my current research project.

It's pretty self-contained, mostly just adding map_groupby* methods to FacetGrid. But that's because I make GroupBy mimic the underlying DataArray by adding coords, attrs and __getitem__.

This still needs more tests but I would like feedback on the feature and the implementation.

Example

``` python import numpy as np import xarray as xr

time = np.arange(80) da = xr.DataArray(5 * np.sin(2np.pitime/10), coords={"time": time}, dims="time") da["period"] = da.time.where((time % 10) == 0).ffill("time")/10 da.plot() ```

python da.groupby("period").plot(col="period", col_wrap=4)

python da = da.expand_dims(y=10) da.groupby("period").plot(col="period", col_wrap=4, sharex=False, sharey=True, robust=True)