Removals

Top-level cmap registration and access functions in mpl.cm ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

As part of the multi-step refactoring of colormap registration <https://github.com/matplotlib/matplotlib/issues/20853>_, the following functions have been removed:

matplotlib.cm.get_cmap; use matplotlib.colormaps[name] instead if you have a str.

Use matplotlib.cm.ColormapRegistry.get_cmap if you have a str, None or a matplotlib.colors.Colormap object that you want to convert to a .Colormap object.
matplotlib.cm.register_cmap; use matplotlib.colormaps.register <.ColormapRegistry.register> instead.
matplotlib.cm.unregister_cmap; use matplotlib.colormaps.unregister <.ColormapRegistry.unregister> instead.
matplotlib.pyplot.register_cmap; use matplotlib.colormaps.register <.ColormapRegistry.register> instead.

The matplotlib.pyplot.get_cmap function will stay available for backward compatibility.

Contour labels ^^^^^^^^^^^^^^

contour.ClabelText and ContourLabeler.set_label_props are removed. Use Text(..., transform_rotates_text=True) as a replacement for contour.ClabelText(...) and text.set(text=text, color=color, fontproperties=labeler.labelFontProps, clip_box=labeler.axes.bbox) as a replacement for the ContourLabeler.set_label_props(label, text, color).

The labelFontProps, labelFontSizeList, and labelTextsList attributes of .ContourLabeler have been removed. Use the labelTexts attribute and the font properties of the corresponding text objects instead.

num2julian, julian2num and JULIAN_OFFSET ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

... of the .dates module are removed without replacements. These were undocumented and not exported.

Julian dates in Matplotlib were calculated from a Julian date epoch: jdate = (date - np.datetime64(EPOCH)) / np.timedelta64(1, 'D'). Conversely, a Julian date was converted to datetime as date = np.timedelta64(int(jdate * 24 * 3600), 's') + np.datetime64(EPOCH). Matplotlib was using EPOCH='-4713-11-24T12:00' so that 2000-01-01 at 12:00 is 2_451_545.0 (see https://en.wikipedia.org/wiki/Julian_day).

offsetbox methods ^^^^^^^^^^^^^^^^^^^^^

offsetbox.bbox_artist is removed. This was just a wrapper to call .patches.bbox_artist if a flag is set in the file, so use that directly if you need the behavior.

OffsetBox.get_extent_offsets and OffsetBox.get_extent are removed; these methods are also removed on all subclasses of .OffsetBox. To get the offsetbox extents, instead of get_extent, use .OffsetBox.get_bbox, which directly returns a .Bbox instance. To also get the child offsets, instead of get_extent_offsets, separately call ~.OffsetBox.get_offset on each children after triggering a draw.

parse_fontconfig_pattern raises on unknown constant names ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

Previously, in a fontconfig pattern like DejaVu Sans:foo, the unknown foo constant name would be silently ignored. This now raises an error.

tri submodules ^^^^^^^^^^^^^^^^^^

The matplotlib.tri.* submodules are removed. All functionality is available in matplotlib.tri directly and should be imported from there.

Widget API ^^^^^^^^^^

CheckButtons.rectangles and CheckButtons.lines are removed; .CheckButtons now draws itself using ~.Axes.scatter.
RadioButtons.circles is removed; .RadioButtons now draws itself using ~.Axes.scatter.
MultiCursor.needclear is removed with no replacement.
The unused parameter x to TextBox.begin_typing was a required argument, and is now removed.

Most arguments to widgets have been made keyword-only """""""""""""""""""""""""""""""""""""""""""""""""""""

Passing all but the very few first arguments positionally in the constructors of Widgets is now keyword-only. In general, all optional arguments are keyword-only.

Axes3D API ^^^^^^^^^^^^^^

Axes3D.unit_cube, Axes3D.tunit_cube, and Axes3D.tunit_edges are removed without replacement.
axes3d.vvec, axes3d.eye, axes3d.sx, and axes3d.sy are removed without replacement.

Inconsistent nth_coord and loc passed to _FixedAxisArtistHelperBase ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

The value of the nth_coord parameter of _FixedAxisArtistHelperBase and its subclasses is now inferred from the value of loc; passing inconsistent values (e.g., requesting a "top y axis" or a "left x axis") has no more effect.

Passing undefined label_mode to Grid ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

... is no longer allowed. This includes mpl_toolkits.axes_grid1.axes_grid.Grid, mpl_toolkits.axes_grid1.axes_grid.AxesGrid, and mpl_toolkits.axes_grid1.axes_grid.ImageGrid as well as the corresponding classes imported from mpl_toolkits.axisartist.axes_grid.

Pass label_mode='keep' instead to get the previous behavior of not modifying labels.

draw_gouraud_triangle ^^^^^^^^^^^^^^^^^^^^^^^^^

... is removed. Use ~.RendererBase.draw_gouraud_triangles instead.

A draw_gouraud_triangle call in a custom ~matplotlib.artist.Artist can readily be replaced as::

self.draw_gouraud_triangles(gc, points.reshape((1, 3, 2)),
                            colors.reshape((1, 3, 4)), trans)

A ~.RendererBase.draw_gouraud_triangles method can be implemented from an existing draw_gouraud_triangle method as::

transform = transform.frozen()
for tri, col in zip(triangles_array, colors_array):
    self.draw_gouraud_triangle(gc, tri, col, transform)

Miscellaneous removals ^^^^^^^^^^^^^^^^^^^^^^

The following items have previously been replaced, and are now removed:

ticklabels parameter of matplotlib.axis.Axis.set_ticklabels has been renamed to labels.
Barbs.barbs_doc and Quiver.quiver_doc are removed. These are the doc-strings and should not be accessible as a named class member, but as normal doc-strings would.
collections.PolyCollection.span_where and collections.BrokenBarHCollection; use fill_between instead.
Legend.legendHandles was undocumented and has been renamed to legend_handles.

The following items have been removed without replacements:

The attributes repeat of .TimedAnimation and subclasses and save_count of .FuncAnimation are considered private and removed.
matplotlib.backend.backend_agg.BufferRegion.to_string
matplotlib.backend.backend_agg.BufferRegion.to_string_argb
matplotlib.backends.backend_ps.PsBackendHelper
matplotlib.backends.backend_webagg.ServerThread
raw parameter of .GridSpecBase.get_grid_positions
matplotlib.patches.ConnectionStyle._Base.SimpleEvent
passthru_pt attribute of mpl_toolkits.axisartist.AxisArtistHelper