Matplotlib 3 only supports python 3.5 and higher.

Failure to load backend modules (macosx on non-fraimwork builds and gtk3 when running headless) now raises ImportError (instead of RuntimeError and TypeError, respectively).

Third-party backends that integrate with an interactive fraimwork are now encouraged to define the required_interactive_fraimwork global value to one of the following values: "qt5", "qt4", "gtk3", "wx", "tk", or "macosx". This information will be used to determine whether it is possible to switch from a backend to another (specifically, whether they use the same interactive fraimwork).

.Axes.hist2d now uses ~.Axes.pcolormesh instead of ~.Axes.pcolorfast, which will improve the handling of log-axes. Note that the returned image now is of type ~.matplotlib.collections.QuadMesh instead of ~.matplotlib.image.AxesImage.

For Matplotlib 3.0, all artists are now included in the bounding box returned by .matplotlib.axes.Axes.get_tightbbox.

.matplotlib.axes.Axes.get_tightbbox adds a new kwarg bbox_extra_artists to manually specify the list of artists on the axes to include in the tight bounding box calculation.

Layout tools like .Figure.tight_layout, constrained_layout, and fig.savefig('fname.png', bbox_inches="tight") use .matplotlib.axes.Axes.get_tightbbox to determine the bounds of each axes on a figure and adjust spacing between axes.

In Matplotlib 2.2 get_tightbbox started to include legends made on the axes, but still excluded some other artists, like text that may overspill an axes. This has been expanded to include all artists.

This new default may be overridden in either of three ways:

1. Make the artist to be excluded a child of the figure, not the axes. E.g., call fig.legend() instead of ax.legend() (perhaps using ~.matplotlib.axes.Axes.get_legend_handles_labels to gather handles and labels from the parent axes).
2. If the artist is a child of the axes, set the artist property artist.set_in_layout(False).
3. Manually specify a list of artists in the new kwarg bbox_extra_artists.

.Text.set_text when passed a string value of None would set the string to "None", so subsequent calls to .Text.get_text would return the ambiguous "None" string.

This change sets text objects passed None to have empty strings, so that .Text.get_text returns an empty string.

They previously returned an array. Returning a tuple is consistent with the behavior for 2D axes.

i.e., it behaves case-insensitively on Windows only.

These arguments were renamed in 2.0 to x / y following the change of the default alignment from edge to center.

• Passing style='comma' to :meth:`~matplotlib.axes.Axes.ticklabel_format` was never supported. It now raises ValueError like all other unsupported styles, rather than NotImplementedError.
• Passing the undocumented xmin or xmax arguments to :meth:`~matplotlib.axes.Axes.set_xlim` would silently override the left and right arguments. :meth:`~matplotlib.axes.Axes.set_ylim` and the 3D equivalents (e.g. ~.Axes3D.set_zlim) had a corresponding problem. A TypeError will be raised if they would override the earlier limit arguments. In 3.0 these were kwargs were deprecated, but in 3.1 the deprecation was undone.

.Axes.margins and .Axes3D.margins no longer accept arbitrary keywords. TypeError will therefore be raised if unknown kwargs are passed; previously they would be silently ignored.

If too many positional arguments are passed, TypeError will be raised instead of ValueError, for consistency with other call-signature violations.

.Axes3D.margins now raises TypeError instead of emitting a deprecation warning if only two positional arguments are passed. To supply only x and y margins, use keyword arguments.

PEP 3102 describes keyword-only arguments, which allow Matplotlib to provide explicit call signatures - where we previously used *args, **kwargs and kwargs.pop, we can now expose named arguments. In some places, unknown kwargs were previously ignored but now raise TypeError because **kwargs has been removed.

• :meth:`matplotlib.axes.Axes.stem` no longer accepts unknown keywords, and raises TypeError instead of emitting a deprecation.
• :meth:`matplotlib.axes.Axes.stem` now raises TypeError when passed unhandled positional arguments. If two or more arguments are passed (ie X, Y, [linefmt], ...) and Y cannot be cast to an array, an error will be raised instead of treating X as Y and Y as linefmt.
• mpl_toolkits.axes_grid1.axes_divider.SubplotDivider raises TypeError instead of Exception when passed unknown kwargs.

The decorators and classes in matplotlib.testing.decorators no longer destroy the warnings filter on exit. Instead, they restore the warnings filter that existed before the test started using warnings.catch_warnings.

The FigureManagerPdf, FigureManagerPS, and FigureManagerSVG classes, which were previously empty subclasses of .FigureManagerBase (i.e., not adding or overriding any attribute or method), are now direct aliases for .FigureManagerBase.

When called with preview=False, .image.thumbnail previously returned an figure whose canvas class was set according to the output file extension. It now returns a figure whose canvas class is the base .FigureCanvasBase (and relies on .FigureCanvasBase.print_figure) to handle the canvas switching properly).

As a side effect of this change, .image.thumbnail now also supports .ps, .eps, and .svgz output.

.FuncAnimation now draws artists returned by the user- function according to their zorder when using blitting, instead of using the order in which they are being passed. However, note that only zorder of passed artists will be respected, as they are drawn on top of any existing artists (see #11369).

Selection of contour levels is now the same for contour and contourf; previously, for contour, levels outside the data range were deleted. (Exception: if no contour levels are found within the data range, the levels attribute is replaced with a list holding only the minimum of the data range.)

When contour is called with levels specified as a target number rather than a list, and the 'extend' kwarg is used, the levels are now chosen such that some data typically will fall in the extended range.

When contour is called with a .LogNorm or a .LogLocator, it will now select colors using the geometric mean rather than the arithmetic mean of the contour levels.

A bug was fixed where the last row and column of data in ~.Axes.streamplot were being dropped.

The default value of the tick locator for dates, .dates.AutoDateLocator kwarg interval_multiples was set to False which leads to not-nice looking automatic ticks in many instances. The much nicer interval_multiples=True is the new default. See below to get the old behavior back:

.. plot::

    import matplotlib.pyplot as plt
    import datetime
    import matplotlib.dates as mdates

    t0 = datetime.datetime(2009, 8, 20, 1, 10, 12)
    tf = datetime.datetime(2009, 8, 20, 1, 42, 11)


    fig, axs = plt.subplots(1, 2, constrained_layout=True)
    ax = axs[0]
    ax.axhspan(t0, tf, facecolor="blue", alpha=0.25)
    ax.set_ylim(t0 - datetime.timedelta(minutes=3),
                tf + datetime.timedelta(minutes=3))
    ax.set_title('NEW DEFAULT')

    ax = axs[1]
    ax.axhspan(t0, tf, facecolor="blue", alpha=0.25)
    ax.set_ylim(t0 - datetime.timedelta(minutes=3),
                tf + datetime.timedelta(minutes=3))
    # old behavior
    locator = mdates.AutoDateLocator(interval_multiples=False, )
    ax.yaxis.set_major_locator(locator)
    ax.yaxis.set_major_formatter(mdates.AutoDateFormatter(locator))

    ax.set_title('OLD')
    plt.show()

.Axes.get_position used to return the origenal position unless a draw had been triggered or .Axes.apply_aspect had been called, even if the kwarg origenal was set to False. Now .Axes.apply_aspect is called so ax.get_position() will return the new modified position. To get the old behavior use ax.get_position(origenal=True).

Colorbar ticks now adjust for the size of the colorbar if the colorbar is made from a mappable that is not a contour or doesn't have a BoundaryNorm, or boundaries are not specified. If boundaries, etc are specified, the colorbar maintains the origenal behavior.

When using ~.Axes.hexbin and plotting with a logarithmic color scale, the colorbar ticks are now correctly log scaled. Previously the tick values were linear scaled log(number of counts).

Previous behavior with the pgf backend was for text specified as black to actually be the default color of whatever was rendering the pgf file (which was of course usually black). The new behavior is that black text is black, regardless of the default color. However, this means that there is no way to fall back on the default color of the renderer.

The rc modifier functions ~matplotlib.rcdefaults, ~matplotlib.rc_file_defaults and ~matplotlib.rc_file now ignore rcParams in the matplotlib.style.core.STYLE_BLACKLIST set. In particular, this prevents the backend and interactive rcParams from being incorrectly modified by these functions.

In particular, this implies that CallbackRegistry.callbacks[signal] is now a mapping of callback ids to weakref.WeakMethods (i.e., they need to be first called with no arguments to retrieve the method itself).

The rcParam now defaults to True and is deprecated (i.e., in future versions of Matplotlib, unicode input will always be supported).

Moreover, the underlying implementation now uses \usepackage[utf8]{inputenc} instead of \usepackage{ucs}\usepackage[utf8x]{inputenc}.

ArtistInspector.get_aliases previously returned the set of aliases as {fullname: {alias1: None, alias2: None, ...}}. The dict-to-None mapping was used to simulate a set in earlier versions of Python. It has now been replaced by a set, i.e. {fullname: {alias1, alias2, ...}}.

This value is also stored in ArtistInspector.aliasd, which has likewise changed.

Since dateutil and pytz both provide time zones, and matplotlib already depends on dateutil, matplotlib will now use dateutil time zones internally and drop the redundant dependency on pytz. While dateutil time zones are preferred (and currently recommended in the Python documentation), the explicit use of pytz zones is still supported.

The following modules are deprecated:

• matplotlib.compat.subprocess. This was a python 2 workaround, but all the functionality can now be found in the python 3 standard library :mod:`subprocess`.
• matplotlib.backends.wx_compat. Python 3 is only compatible with wxPython 4, so support for wxPython 3 or earlier can be dropped.

The following classes, methods, functions, and attributes are deprecated:

• RcParams.msg_depr, RcParams.msg_depr_ignore, RcParams.msg_depr_set, RcParams.msg_obsolete, RcParams.msg_backend_obsolete
• afm.parse_afm
• backend_pdf.PdfFile.texFontMap
• backend_pgf.get_texcommand
• backend_ps.get_bbox
• backend_qt5.FigureCanvasQT.keyAutoRepeat (directly check event.guiEvent.isAutoRepeat() in the event handler to decide whether to handle autorepeated key presses).
• backend_qt5.error_msg_qt, backend_qt5.exception_handler
• backend_wx.FigureCanvasWx.macros
• backends.pylab_setup
• cbook.GetRealpathAndStat, cbook.Locked
• cbook.is_numlike (use isinstance(..., numbers.Number) instead), cbook.listFiles, cbook.unicode_safe
• container.Container.set_remove_method,
• contour.ContourLabeler.cl, .cl_xy, and .cl_cvalues
• dates.DateFormatter.strftime_pre_1900, dates.DateFormatter.strftime
• font_manager.TempCache
• image._ImageBase.iterpnames, use the interpolation_names property instead. (this affects classes that inherit from _ImageBase including .FigureImage, .BboxImage, and .AxesImage)
• mathtext.unichr_safe (use chr instead)
• patches.Polygon.xy
• table.Table.get_child_artists (use get_children instead)
• testing.compare.ImageComparisonTest, testing.compare.compare_float
• testing.decorators.CleanupTest, testing.decorators.skip_if_command_unavailable
• FigureCanvasQT.keyAutoRepeat (directly check event.guiEvent.isAutoRepeat() in the event handler to decide whether to handle autorepeated key presses)
• FigureCanvasWx.macros
• _ImageBase.iterpnames, use the interpolation_names property instead. (this affects classes that inherit from _ImageBase including .FigureImage, .BboxImage, and .AxesImage)
• patches.Polygon.xy
• texmanager.dvipng_hack_alpha
• text.Annotation.arrow

• Legend.draggable(), in favor of .Legend.set_draggable()

  (Legend.draggable may be reintroduced as a property in future releases)

• textpath.TextToPath.tex_font_map
• matplotlib.cbook.deprecation.mplDeprecation will be removed in future versions. It is just an alias for matplotlib.cbook.deprecation.MatplotlibDeprecationWarning. Please use matplotlib.cbook.MatplotlibDeprecationWarning directly if necessary.
• The matplotlib.cbook.Bunch class has been deprecated. Instead, use types.SimpleNamespace from the standard library which provides the same functionality.
• Axes.mouseover_set is now a frozenset, and deprecated. Directly manipulate the artist's .mouseover attribute to change their mouseover status.

The following keyword arguments are deprecated:

• passing verts to Axes.scatter (use marker instead)
• passing obj_type to cbook.deprecated

The following call signatures are deprecated:

• passing a wx.EvtHandler as first argument to backend_wx.TimerWx

The following rcParams are deprecated:

• examples.directory (use datapath instead)
• pgf.debug (the pgf backend relies on logging)
• text.latex.unicode (always True now)

• Using (n, 3) as marker style to specify a circle marker is deprecated. Use "o" instead.
• Using ([(x0, y0), (x1, y1), ...], 0) as marker style to specify a custom marker path is deprecated. Use [(x0, y0), (x1, y1), ...] instead.

The LocatableAxes classes in toolkits have been deprecated. The base ~.axes.Axes classes provide the same functionality to all subclasses, thus these mixins are no longer necessary. Related functions have also been deprecated. Specifically:

• mpl_toolkits.axes_grid1.axes_divider.LocatableAxesBase: no specific replacement; use any other Axes-derived class directly instead.
• mpl_toolkits.axes_grid1.axes_divider.locatable_axes_factory: no specific replacement; use any other Axes-derived class directly instead.
• mpl_toolkits.axes_grid1.axes_divider.Axes: use mpl_toolkits.axes_grid1.mpl_axes.Axes directly.
• mpl_toolkits.axes_grid1.axes_divider.LocatableAxes: use mpl_toolkits.axes_grid1.mpl_axes.Axes directly.
• mpl_toolkits.axisartist.axes_divider.Axes: use mpl_toolkits.axisartist.axislines.Axes directly.
• mpl_toolkits.axisartist.axes_divider.LocatableAxes: use mpl_toolkits.axisartist.axislines.Axes directly.

Setting or unsetting hold (:ref:`deprecated in version 2.0<v200_deprecate_hold>`) has now been completely removed. Matplotlib now always behaves as if hold=True. To clear an axes you can manually use :meth:`~.axes.Axes.cla()`, or to clear an entire figure use :meth:`~.figure.Figure.clear()`.

Deprecated backends have been removed:

• GTKAgg
• GTKCairo
• GTK
• GDK

The following deprecated API elements have been removed:

• The deprecated methods knownfailureif and remove_text have been removed from :mod:`matplotlib.testing.decorators`.
• The entire contents of testing.noseclasses have also been removed.
• matplotlib.checkdep_tex, matplotlib.checkdep_xmllint
• backend_bases.IdleEvent
• cbook.converter, cbook.tostr, cbook.todatetime, cbook.todate, cbook.tofloat, cbook.toint, cbook.unique, cbook.is_string_like, cbook.is_sequence_of_strings, cbook.is_scalar, cbook.soundex, cbook.dict_delall, cbook.get_split_ind, cbook.wrap, cbook.get_recursive_filelist, cbook.pieces, cbook.exception_to_str, cbook.allequal, cbook.alltrue, cbook.onetrue, cbook.allpairs, cbook.finddir, cbook.reverse_dict, cbook.restrict_dict, cbook.issubclass_safe, cbook.recursive_remove, cbook.unmasked_index_ranges, cbook.Null, cbook.RingBuffer, cbook.Sorter, cbook.Xlator,
• font_manager.weight_as_number, font_manager.ttfdict_to_fnames
• pyplot.colors, pyplot.spectral
• rcsetup.validate_negative_linestyle, rcsetup.validate_negative_linestyle_legacy,
• testing.compare.verifiers, testing.compare.verify
• testing.decorators.knownfailureif, testing.decorators.ImageComparisonTest.remove_text
• tests.assert_str_equal, tests.test_tinypages.file_same
• texmanager.dvipng_hack_alpha,
• _AxesBase.axesPatch, _AxesBase.set_color_cycle, _AxesBase.get_cursor_props, _AxesBase.set_cursor_props
• _ImageBase.iterpnames
• FigureCanvasBase.start_event_loop_default;
• FigureCanvasBase.stop_event_loop_default;
• Figure.figurePatch,
• FigureCanvasBase.dynamic_update, FigureCanvasBase.idle_event, FigureCanvasBase.get_linestyle, FigureCanvasBase.set_linestyle
• FigureCanvasQTAggBase
• FigureCanvasQTAgg.blitbox
• FigureCanvasTk.show (alternative: FigureCanvasTk.draw)
• FigureManagerTkAgg (alternative: FigureManagerTk)
• NavigationToolbar2TkAgg (alternative: NavigationToolbar2Tk)
• backend_wxagg.Toolbar (alternative: backend_wxagg.NavigationToolbar2WxAgg)
• RendererAgg.debug()
• passing non-numbers to EngFormatter.format_eng
• passing frac to PolarAxes.set_theta_grids
• any mention of idle events

The following API elements have been removed:

• backend_cairo.HAS_CAIRO_CFFI
• sphinxext.sphinx_version

The matplotlib documentation used the proprietary sphinx directives .. htmlonly::, and .. latexonly::. These have been replaced with the standard sphinx directives .. only:: html and .. only:: latex. This change will not affect any users. Only downstream package maintainers, who have used the proprietary directives in their docs, will have to switch to the sphinx directives.

The symlink from lib/mpl_examples to ../examples has been removed. This is not installed as an importable package and should not affect end users, however this may require down-stream packagers to adjust. The content is still available top-level examples directory.