Switch to use cmap.with_extremes

[Illviljan]

Colormaps are slowly becoming immutable, matplotlib/matplotlib#30531.

• Closes ⚠️ Nightly upstream-dev CI failed ⚠️ #10735 (plotting ones at least)

Fixes the upstream issues:

xarray/tests/test_plot.py::TestPlot::test_contourf_cmap_set_with_bad_under_over: PendingDeprecationWarning: The set_bad function will be deprecated in a future version. Use cmap.with_extremes(bad=...) or Colormap(bad=...) instead.
xarray/tests/test_plot.py::TestDiscreteColorMap::test_discrete_colormap_int_levels: PendingDeprecationWarning: The set_bad function will be deprecated in a future version. Use cmap.with_extremes(bad=...) or Colormap(bad=...) instead.

[ianhi]

set_extremes was introduced in 3.4 https://matplotlib.org/stable/users/prev_whats_new/whats_new_3.4.0.html#colormap-set-extremes-and-colormap-with-extremes

So I think this PR needs to update the xarray matplotlib viz extra to include matplotlib>=3.4. It is currently unbounded

[Illviljan]

So I think this PR needs to update the xarray matplotlib viz extra to include matplotlib>=3.4. It is currently unbounded

Odd, our minimum version policy says 3.8:

Details

 ╭─────────────────────────────────────────────── min-all-deps ───────────────────────────────────────────────╮
│                  ┏━━━━━━━━━━━━━━━━━━━━━━┳━━━━━━━━━━┳━━━━━━━━━━━━━━━━━┳━━━━━━━━━━┳━━━━━━━━━━━━━━━┳━━━━━━━━┓ │
│                  ┃ Package              ┃ Required ┃ Required (date) ┃ Policy   ┃ Policy (date) ┃ Status ┃ │
│                  ┡━━━━━━━━━━━━━━━━━━━━━━╇━━━━━━━━━━╇━━━━━━━━━━━━━━━━━╇━━━━━━━━━━╇━━━━━━━━━━━━━━━╇━━━━━━━━┩ │
│                  │ python               │ 3.11     │ 2022-10-25      │ 3.11     │ 2022-10-25    │ =      │ │
│                  │ array-api-strict     │ 1.1      │ 2024-03-09      │ 2.0      │ 2024-06-28    │ <      │ │
│                  │ boto3                │ 1.34     │ 2023-12-14      │ 1.35     │ 2024-08-17    │ <      │ │
│                  │ bottleneck           │ 1.4      │ 2024-06-18      │ 1.4      │ 2024-06-18    │ =      │ │
│                  │ cartopy              │ 0.23     │ 2024-04-11      │ 0.24     │ 2024-10-07    │ <      │ │
│                  │ cftime               │ 1.6      │ 2022-03-03      │ 1.6      │ 2022-03-03    │ =      │ │
│                  │ dask-core            │ 2024.6   │ 2024-06-14      │ 2024.9   │ 2024-09-13    │ <      │ │
│                  │ distributed          │ 2024.6   │ 2024-06-14      │ 2024.9   │ 2024-09-13    │ <      │ │
│                  │ flox                 │ 0.9      │ 2024-01-23      │ 0.9      │ 2024-01-23    │ =      │ │
│                  │ h5netcdf             │ 1.3      │ 2023-11-08      │ 1.4      │ 2024-10-07    │ <      │ │
│                  │ h5py                 │ 3.11     │ 2024-04-10      │ 3.11     │ 2024-04-10    │ =      │ │
│                  │ hdf5                 │ 1.14     │ 2023-02-05      │ 1.14     │ 2023-02-05    │ =      │ │
│                  │ iris                 │ 3.9      │ 2024-04-22      │ 3.10     │ 2024-08-13    │ <      │ │
│ Version summary  │ lxml                 │ 5.1      │ 2024-01-08      │ 5.3      │ 2024-08-12    │ <      │ │
│                  │ matplotlib-base      │ 3.8      │ 2023-09-18      │ 3.8      │ 2023-09-18    │ =      │ │
│                  │ nc-time-axis         │ 1.4      │ 2021-10-23      │ 1.4      │ 2021-10-23    │ =      │ │
│                  │ netcdf4              │ 1.6      │ 2022-06-29      │ 1.6      │ 2022-06-29    │ =      │ │
│                  │ numba                │ 0.60     │ 2024-06-20      │ 0.60     │ 2024-06-20    │ =      │ │
│                  │ numbagg              │ 0.8      │ 2024-02-03      │ 0.8      │ 2024-02-03    │ =      │ │
│                  │ numpy                │ 1.26     │ 2023-09-17      │ 1.26     │ 2023-09-17    │ =      │ │
│                  │ packaging            │ 24.1     │ 2024-06-12      │ 24.1     │ 2024-06-12    │ =      │ │
│                  │ pandas               │ 2.2      │ 2024-01-20      │ 2.2      │ 2024-01-20    │ =      │ │
│                  │ pint                 │ 0.24     │ 2024-06-11      │ 0.24     │ 2024-06-11    │ =      │ │
│                  │ pydap                │ 3.5.0    │ 2024-08-21      │ 3.5      │ 2024-08-21    │ =      │ │
│                  │ rasterio             │ 1.3      │ 2022-07-06      │ 1.4      │ 2024-09-27    │ <      │ │
│                  │ scipy                │ 1.13     │ 2024-04-04      │ 1.14     │ 2024-06-25    │ <      │ │
│                  │ seaborn              │ 0.13     │ 2023-10-02      │ 0.13     │ 2023-10-02    │ =      │ │
│                  │ sparse               │ 0.15     │ 2024-01-09      │ 0.15     │ 2024-01-09    │ =      │ │
│                  │ toolz                │ 0.12     │ 2022-07-10      │ 1.0      │ 2024-10-04    │ <      │ │
│                  │ zarr                 │ 2.18     │ 2024-05-08      │ 2.18     │ 2024-05-08    │ =      │ │
│                  └──────────────────────┴──────────┴─────────────────┴──────────┴───────────────┴────────┘ │
╰────────────────────────────────────────────────────────────────────────────────────────────────────────────╯

[ianhi]

Odd, our minimum version policy says 3.8:

Ahh that's a much more reasonable bound. Although it's not currently encoded in the actual requirements

xarray/pyproject.toml

Line 50 in 20d3773

viz = ["cartopy>=0.23", "matplotlib", "nc-time-axis", "seaborn"]

[Illviljan]

yeah, I'm not sure why that is. It might be intended:

xarray/pyproject.toml

Lines 23 to 26 in 20d3773

	# We don't encode minimum requirements here (though if we can write a script to
	# generate the text from `min_deps_check.py`, that's welcome...). We do add
	# `numba>=0.54` here because of https://github.com/astral-sh/uv/issues/7881;
	# note that it's not a direct dependency of xarray.

[Illviljan]

Only the unrelated pandas error left now:

 =========================== short test summary info ============================
FAILED properties/test_pandas_roundtrip.py::test_roundtrip_1d_pandas_extension_array[False-string] - assert <StringDtype(na_value=<NA>)> == <StringDtype(na_value=nan)>
 +  where <StringDtype(na_value=<NA>)> = 0    a\n1    b\n2    c\nName: arr, dtype: string.dtype
 +  and   <StringDtype(na_value=nan)> = index\n0    a\n1    b\n2    c\nName: arr, dtype: str.dtype