Matplotlib 3.0 is here with new cyclic colormaps, and convenience methods

Matplotlib team announced Matplotlib version 3.0, on Tuesday. Matplotlib 3.0 comes with new features such as two new cyclic colormaps, AnchoredDirectionArrows feature, and other updates and improvements.

Matplotlib is a plotting library for the Python programming language as well as for its numerical mathematics extension, NumPy. It offers an object-oriented API for embedding plots into applications using general-purpose GUI toolkits such as Tkinter, wxPython, Qt, or GTK+.

Let’s have a look at what’s new in this latest release.

Cyclic Colormaps

Two new colormaps namely 'twilight' and 'twilight_shifted' have been added to this new release. These two colormaps start and end on the same color. They have two symmetric halves with equal lightness, but diverging color.

AnchoredDirectionArrows added to mpl_toolkits

A new mpl_toolkit class AnchoredDirectionArrows, has been added in this release.

AnchoredDirectionArrows draws a pair of orthogonal arrows which helps indicate directions on a 2D plot.

Several optional parameters can alter the layout of these arrows. For instance, the arrow pairs can be rotated and their color can be changed. The labels and the arrows have the same color by default, but the class may also pass arguments for customizing arrow and text layout. Other than that, the location, length, and width of both the arrows can also be adjusted.

Improved default backend selection

The default backend needs no longer be set as part of the build process. Instead, builtin backends are tried in sequence at run time, until one of the imports.

Also, Headless Linux servers cannot select a GUI backend.

Scale axis by a fixed order of magnitude

With Matplotlib 3.0, you can scale an axis by a fixed order of magnitude by setting the scilimits argument of Axes.ticklabel_format to the same (non-zero) lower and upper limits. With this setting, the order of magnitude gets adjusted depending on the axis values, rather than remaining fixed.

minorticks_on()/off() methods added for colorbar

A new method colorbar.Colobar.minorticks_on() has been added in this new release that can correctly display the minor ticks on a colorbar. This method doesn't allow the minor ticks to extend into the regions beyond vmin and vmax. A complementary method named colorbar.Colobar.minorticks_off() has also been added for removing the minor ticks on the colorbar.