matplotlib.projections#

Non-separable transforms that map from data space to screen space.

Projections are defined asAxes subclasses. They include thefollowing elements:

• A transformation from data coordinates into display coordinates.

• An inverse of that transformation. This is used, for example, to convertmouse positions from screen space back into data space.

• Transformations for the gridlines, ticks and ticklabels. Custom projectionswill often need to place these elements in special locations, and Matplotlibhas a facility to help with doing so.

• Setting up default values (overridingcla), since the defaultsfor a rectilinear Axes may not be appropriate.

• Defining the shape of the Axes, for example, an elliptical Axes, that will beused to draw the background of the plot and for clipping any data elements.

• Defining custom locators and formatters for the projection. For example, ina geographic projection, it may be more convenient to display the grid indegrees, even if the data is in radians.

• Set up interactive panning and zooming. This is left as an "advanced"feature left to the reader, but there is an example of this for polar plotsinmatplotlib.projections.polar.

• Any additional methods for additional convenience or features.

Once the projection Axes is defined, it can be used in one of two ways:

• By defining the class attributename, the projection Axes can beregistered withmatplotlib.projections.register_projection and subsequentlysimply invoked by name:

  fig.add_subplot(projection="my_proj_name")

• For more complex, parameterisable projections, a generic "projection" objectmay be defined which includes the method_as_mpl_axes._as_mpl_axesshould take no arguments and return the projection's Axes subclass and adictionary of additional arguments to pass to the subclass'__init__method. Subsequently a parameterised projection can be initialised with:

  fig.add_subplot(projection=MyProjection(param1=param1_value))

  where MyProjection is an object which implements a_as_mpl_axes method.

A full-fledged and heavily annotated example is inCustom projection. The polar plot functionality inmatplotlib.projections.polar may also be of interest.

classmatplotlib.projections.ProjectionRegistry[source]#

Bases:object

A mapping of registered projection names to projection classes.

get_projection_class(name)[source]#

Get a projection class from itsname.

get_projection_names()[source]#

Return the names of all projections currently registered.

register(*projections)[source]#

Register a new set of projections.

matplotlib.projections.get_projection_class(projection=None)[source]#

Get a projection class from its name.

Ifprojection is None, a standard rectilinear projection is returned.

matplotlib.projections.get_projection_names()[source]#

Return the names of all projections currently registered.

matplotlib.projections.register_projection(cls)[source]#