Fix colormap handling for Matplotlib 3.11 - #4
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addWhitecm and addColorcm called cm.get_cmap(name, 256), deprecated in
Matplotlib 3.7 and removed in 3.11:
AttributeError: module 'matplotlib.cm' has no attribute 'get_cmap'
setup.py requires matplotlib>=3.10.9 with no upper bound, so a fresh
install resolves to 3.11 and every colour-filled plot raises.
The documented replacement for get_cmap(name, lut) is
matplotlib.colormaps[name].resampled(lut). Two details of the old
behaviour are worth keeping, so this goes through a small helper:
- get_cmap also accepted a Colormap instance and returned it unchanged.
psectionV and friends assign the result back into Lcolormap[i], so a
reused list feeds a Colormap in on the next call.
- resampled() returns a new object, so the set_under/set_over calls in
addColorcm no longer risk mutating the registered colormap.
Verified against matplotlib 3.11.1: colormap by name, Colormap
passthrough, addColorcm, addWhitecm, and a Colormap fed back in.
The same two calls exist in Meso-NH's copies of this module
(src/LIB/Python and examples/integration_cases/hpc/OCEAN_LES/005_python)
and are broken there too.
Matplotlib 3.11 marks both as pending deprecation:
PendingDeprecationWarning: The set_under function will be deprecated
in a future version. Use cmap.with_extremes(under=...) or
Colormap(under=...) instead.
with_extremes returns a new colormap rather than mutating in place,
which also removes the last way addColorcm could modify a Colormap
handed to it by the caller. Available since Matplotlib 3.4, so it is
safe against the declared floor of 3.10.9.
Verified on 3.11.1 and 3.10.9 with warnings raised as errors.
The removed matplotlib.cm.get_cmap mapped name=None to rcParams['image.cmap']. The helper did not, so an explicit None in Lcolormap would raise KeyError where it previously plotted with the default colormap. Lcolormap is seeded with 'gist_rainbow_r' when empty, so None only arrives if a caller passes it, but this keeps the replacement a strict drop-in.
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matplotlib.cm.get_cmapwas removed in Matplotlib 3.11, andsetup.pyallowsmatplotlib>=3.10.9uncapped — so a fresh install breaks on every filled plot:Replaced with
matplotlib.colormaps[name].resampled(lut)behind a small helper that keeps the original's handling ofNoneand ofColormapinstances (psectionV/psectionHfeed one back in throughLcolormap[i]). Also swapsset_under/set_over, pending deprecation in 3.11, forColormap.with_extremes.Output is bit-identical, checked on six colormaps of both classes. Verified on 3.11.1 and 3.10.9 with warnings as errors.
Meso-NH vendors a byte-identical copy of this file at
src/LIB/Python/, broken the same way.