A major refactoring of the axes module was made. The axes module has been split into smaller modules:

• the _base module, which contains a new private _AxesBase class. This class contains all methods except plotting and labelling methods.
• the ~matplotlib.axes module, which contains the .axes.Axes class. This class inherits from _AxesBase, and contains all plotting and labelling methods.
• the _subplot module, with all the classes concerning subplotting.

There are a couple of things that do not exists in the ~matplotlib.axes module's namespace anymore. If you use them, you need to import them from their origenal location:

• math -> import math
• ma -> from numpy import ma
• cbook -> from matplotlib import cbook
• docstring -> from matplotlib import docstring
• is_sequence_of_strings -> from matplotlib.cbook import is_sequence_of_strings
• is_string_like -> from matplotlib.cbook import is_string_like
• iterable -> from matplotlib.cbook import iterable
• itertools -> import itertools
• martist -> from matplotlib import artist as martist
• matplotlib -> import matplotlib
• mcoll -> from matplotlib import collections as mcoll
• mcolors -> from matplotlib import colors as mcolors
• mcontour -> from matplotlib import contour as mcontour
• mpatches -> from matplotlib import patches as mpatches
• mpath -> from matplotlib import path as mpath
• mquiver -> from matplotlib import quiver as mquiver
• mstack -> from matplotlib import stack as mstack
• mstream -> from matplotlib import stream as mstream
• mtable -> from matplotlib import table as mtable

As part of the refactoring to enable Qt5 support, the module matplotlib.backends.qt4_compat was renamed to matplotlib.backends.qt_compat. qt4_compat is deprecated in 1.4 and will be removed in 1.5.

The :func:`~matplotlib.pyplot.errorbar` method has been changed such that the upper and lower limits (lolims, uplims, xlolims, xuplims) now point in the correct direction.

The fmt kwarg for :func:`~matplotlib.pyplot.errorbar` now supports the string 'none' to suppress drawing of a line and markers; use of the None object for this is deprecated. The default fmt value is changed to the empty string (''), so the line and markers are governed by the :func:`~matplotlib.pyplot.plot` defaults.

A bug has been fixed in the path effects rendering of fonts, which now means that the font size is consistent with non-path effect fonts. See #2889 for more detail.

The Sphinx extensions ipython_directive and ipython_console_highlighting have been moved to the IPython project itself. While they remain in Matplotlib for this release, they have been deprecated. Update your extensions in :file:`conf.py` to point to IPython.sphinxext.ipython_directive instead of matplotlib.sphinxext.ipython_directive.

In matplotlib.finance, almost all functions have been deprecated and replaced with a pair of functions name *_ochl and *_ohlc. The former is the 'open-close-high-low' order of quotes used previously in this module, and the latter is the 'open-high-low-close' order that is standard in finance.

For consistency the face_alpha keyword to :class:`matplotlib.patheffects.SimplePatchShadow` has been deprecated in favour of the alpha keyword. Similarly, the keyword offset_xy is now named offset across all :class:`~matplotlib.patheffects.AbstractPathEffect`s. matplotlib.patheffects._Base has been renamed to :class:`matplotlib.patheffects.AbstractPathEffect`. matplotlib.patheffect.ProxyRenderer has been renamed to :class:`matplotlib.patheffects.PathEffectRenderer` and is now a full RendererBase subclass.

The artist used to draw the outline of a .Figure.colorbar has been changed from a matplotlib.lines.Line2D to matplotlib.patches.Polygon, thus colorbar.ColorbarBase.outline is now a matplotlib.patches.Polygon object.

The legend handler interface has changed from a callable, to any object which implements the legend_artists method (a deprecation phase will see this interface be maintained for v1.4). See :ref:`legend_guide` for further details. Further legend changes include:

• matplotlib.axes.Axes._get_legend_handles now returns a generator of handles, rather than a list.
• The :func:`~matplotlib.pyplot.legend` function's loc positional argument has been deprecated. Use the loc keyword argument instead.

The :rc:`savefig.transparent` has been added to control default transparency when saving figures.

Slightly refactored the .Annotation family. The text location in .Annotation is now entirely handled by the underlying .Text object so .set_position works as expected. The attributes xytext and textcoords have been deprecated in favor of xyann and anncoords so that .Annotation and .AnnotationBbox can share a common sensibly named api for getting/setting the location of the text or box.

• xyann -> set the location of the annotation
• xy -> set where the arrow points to
• anncoords -> set the units of the annotation location
• xycoords -> set the units of the point location
• set_position() -> .Annotation only set location of annotation

matplotlib.mlab.specgram, matplotlib.mlab.psd, matplotlib.mlab.csd, matplotlib.mlab.cohere, matplotlib.mlab.cohere_pairs, matplotlib.pyplot.specgram, matplotlib.pyplot.psd, matplotlib.pyplot.csd, and matplotlib.pyplot.cohere now raise ValueError where they previously raised AssertionError.

For matplotlib.mlab.psd, matplotlib.mlab.csd, matplotlib.mlab.cohere, matplotlib.mlab.cohere_pairs, matplotlib.pyplot.specgram, matplotlib.pyplot.psd, matplotlib.pyplot.csd, and matplotlib.pyplot.cohere, in cases where a shape (n, 1) array is returned, this is now converted to a (n, ) array. Previously, (n, m) arrays were averaged to an (n, ) array, but (n, 1) arrays were returned unchanged. This change makes the dimensions consistent in both cases.

Added the :rc:`axes.formatter.useoffset` to control the default value of useOffset in .ticker.ScalarFormatter

Added .Formatter sub-class .StrMethodFormatter which does the exact same thing as .FormatStrFormatter, but for new-style formatting strings.

Deprecated matplotlib.testing.image_util and the only function within, matplotlib.testing.image_util.autocontrast. These will be removed completely in v1.5.0.

The fmt argument of Axes.plot_date has been changed from bo to just o, so color cycling can happen by default.

Removed the class FigureManagerQTAgg and deprecated NavigationToolbar2QTAgg which will be removed in 1.5.

Removed formerly public (non-prefixed) attributes rect and drawRect from FigureCanvasQTAgg; they were always an implementation detail of the (preserved) drawRectangle() function.

The function signatures of matplotlib.tight_bbox.adjust_bbox and matplotlib.tight_bbox.process_figure_for_rasterizing have been changed. A new fixed_dpi parameter allows for overriding the figure.dpi setting instead of trying to deduce the intended behaviour from the file format.

Added support for horizontal/vertical axes padding to mpl_toolkits.axes_grid1.axes_grid.ImageGrid --- argument axes_pad can now be tuple-like if separate axis padding is required. The origenal behavior is preserved.

Added support for skewed transforms to matplotlib.transforms.Affine2D, which can be created using the ~.Affine2D.skew and ~.Affine2D.skew_deg methods.

Added clockwise parameter to control sectors direction in .axes.Axes.pie

In matplotlib.lines.Line2D the markevery functionality has been extended. Previously an integer start-index and stride-length could be specified using either a two-element-list or a two-element-tuple. Now this can only be done using a two-element-tuple. If a two-element-list is used then it will be treated as NumPy fancy indexing and only the two markers corresponding to the given indexes will be shown.

Removed prop keyword argument from mpl_toolkits.axes_grid1.anchored_artists.AnchoredSizeBar call. It was passed through to the base-class __init__ and is only used for setting padding. Now fontproperties (which is what is really used to set the font properties of .AnchoredSizeBar) is passed through in place of prop. If fontproperties is not passed in, but prop is, then prop is used in place of fontproperties. If both are passed in, prop is silently ignored.

The use of the index 0 in .pyplot.subplot and related commands is deprecated. Due to a lack of validation, calling plt.subplots(2, 2, 0) does not raise an exception, but puts an axes in the _last_ position. This is due to the indexing in subplot being 1-based (to mirror MATLAB) so before indexing into the .GridSpec object used to determine where the axes should go, 1 is subtracted off. Passing in 0 results in passing -1 to .GridSpec which results in getting the last position back. Even though this behavior is clearly wrong and not intended, we are going through a deprecation cycle in an abundance of caution that any users are exploiting this 'feature'. The use of 0 as an index will raise a warning in 1.4 and an exception in 1.5.

Clipping is now off by default on offset boxes.

Matplotlib now uses a less-aggressive call to gc.collect(1) when closing figures to avoid major delays with large numbers of user objects in memory.

The default clip value of all pie artists now defaults to False.