diff --git a/doc/api/prev_api_changes/api_changes_3.6.0/deprecations.rst b/doc/api/prev_api_changes/api_changes_3.6.0/deprecations.rst index d59077d2b2d2..3a9e91e12289 100644 --- a/doc/api/prev_api_changes/api_changes_3.6.0/deprecations.rst +++ b/doc/api/prev_api_changes/api_changes_3.6.0/deprecations.rst @@ -52,7 +52,12 @@ In Matplotlib 3.6 we have marked those top level functions as pending deprecation with the intention of deprecation in Matplotlib 3.7. The following functions have been marked for pending deprecation: -- ``matplotlib.cm.get_cmap``; use ``matplotlib.colormaps[name]`` instead +- ``matplotlib.cm.get_cmap``; use ``matplotlib.colormaps[name]`` instead if you + have a `str`. + + **Added 3.6.1** Use `matplotlib.cm.ColormapRegistry.get_cmap` if you + have a string, `None` or a `matplotlib.colors.Colormap` object that you want + to convert to a `matplotlib.colors.Colormap` instance. - ``matplotlib.cm.register_cmap``; use `matplotlib.colormaps.register <.ColormapRegistry.register>` instead - ``matplotlib.cm.unregister_cmap``; use `matplotlib.colormaps.unregister @@ -305,7 +310,7 @@ Backend-specific deprecations private functions if you rely on it. - ``backend_svg.generate_transform`` and ``backend_svg.generate_css`` - ``backend_tk.NavigationToolbar2Tk.lastrect`` and - ``backend_tk.RubberbandTk.lastrect`` + ``backend_tk.RubberbandTk.lastrect`` - ``backend_tk.NavigationToolbar2Tk.window``; use ``toolbar.master`` instead. - ``backend_tools.ToolBase.destroy``; To run code upon tool removal, connect to the ``tool_removed_event`` event. diff --git a/lib/matplotlib/cm.py b/lib/matplotlib/cm.py index f6e5ee8b7156..ec0d472992ef 100644 --- a/lib/matplotlib/cm.py +++ b/lib/matplotlib/cm.py @@ -61,12 +61,6 @@ class ColormapRegistry(Mapping): r""" Container for colormaps that are known to Matplotlib by name. - .. admonition:: Experimental - - While we expect the API to be final, we formally mark it as - experimental for 3.5 because we want to keep the option to still adapt - the API for 3.6 should the need arise. - The universal registry instance is `matplotlib.colormaps`. There should be no need for users to instantiate `.ColormapRegistry` themselves. @@ -193,6 +187,38 @@ def unregister(self, name): "colormap.") self._cmaps.pop(name, None) + def get_cmap(self, cmap): + """ + Return a color map specified through *cmap*. + + Parameters + ---------- + cmap : str or `~matplotlib.colors.Colormap` or None + + - if a `.Colormap`, return it + - if a string, look it up in ``mpl.colormaps`` + - if None, return the Colormap defined in :rc:`image.cmap` + + Returns + ------- + Colormap + """ + # get the default color map + if cmap is None: + return self[mpl.rcParams["image.cmap"]] + + # if the user passed in a Colormap, simply return it + if isinstance(cmap, colors.Colormap): + return cmap + if isinstance(cmap, str): + _api.check_in_list(sorted(_colormaps), cmap=cmap) + # otherwise, it must be a string so look it up + return self[cmap] + raise TypeError( + 'get_cmap expects None or an instance of a str or Colormap . ' + + f'you passed {cmap!r} of type {type(cmap)}' + ) + # public access to the colormaps should be via `matplotlib.colormaps`. For now, # we still create the registry here, but that should stay an implementation @@ -281,7 +307,12 @@ def _get_cmap(name=None, lut=None): # pyplot. get_cmap = _api.deprecated( '3.6', - name='get_cmap', pending=True, alternative="``matplotlib.colormaps[name]``" + name='get_cmap', + pending=True, + alternative=( + "``matplotlib.colormaps[name]`` " + + "or ``matplotlib.colormaps.get_cmap(obj)``" + ) )(_get_cmap) @@ -687,6 +718,8 @@ def _ensure_cmap(cmap): """ Ensure that we have a `.Colormap` object. + For internal use to preserve type stability of errors. + Parameters ---------- cmap : None, str, Colormap @@ -698,6 +731,7 @@ def _ensure_cmap(cmap): Returns ------- Colormap + """ if isinstance(cmap, colors.Colormap): return cmap diff --git a/lib/matplotlib/tests/test_colors.py b/lib/matplotlib/tests/test_colors.py index f0c23038e11a..86536ab17234 100644 --- a/lib/matplotlib/tests/test_colors.py +++ b/lib/matplotlib/tests/test_colors.py @@ -109,6 +109,26 @@ def test_register_cmap(): cm.register_cmap('nome', cmap='not a cmap') +def test_colormaps_get_cmap(): + cr = mpl.colormaps + + # check str, and Colormap pass + assert cr.get_cmap('plasma') == cr["plasma"] + assert cr.get_cmap(cr["magma"]) == cr["magma"] + + # check default + assert cr.get_cmap(None) == cr[mpl.rcParams['image.cmap']] + + # check ValueError on bad name + bad_cmap = 'AardvarksAreAwkward' + with pytest.raises(ValueError, match=bad_cmap): + cr.get_cmap(bad_cmap) + + # check TypeError on bad type + with pytest.raises(TypeError, match='object'): + cr.get_cmap(object()) + + def test_double_register_builtin_cmap(): name = "viridis" match = f"Re-registering the builtin cmap {name!r}."