These are the ggplot2 ggplot2::ggproto() classes that back the
circumplex layers and coordinate system: GeomSsmPoint (the profile-point
geom), GeomSsmArc (the confidence-region arc geom), GeomSsmPath (the
movement-path geom), and CoordCircumplex (the coordinate system). They are
exported so that downstream packages can subclass them to build custom
circumplex layers; most users should use the geom_ssm_point(),
geom_ssm_arc(), geom_ssm_path(), and coord_circumplex() constructors
instead.
geom_ssm_point(), geom_ssm_arc(), geom_ssm_path(),
coord_circumplex()