coord_circumplex: Circumplex coordinate system

Description

A ggplot2 coordinate system that maps Structural Summary Method parameters onto the circular circumplex canvas: the displacement aesthetic (degrees, counterclockwise from the right, with the 0/360 pole labelled 360) becomes the angle and the amplitude aesthetic becomes the radius. It owns the amplitude-to-radius scaling, so geom_ssm_point() and geom_ssm_arc() no longer take an amax, and the canvas and data layers can never disagree.

Usage

coord_circumplex(amax = NULL, center = 0, r_axis_angle = NULL, ...)

Value

A ggplot2 coordinate system that can be added to a plot with +.

Arguments

amax: Optional. A single positive number giving the amplitude represented by the outer ring. NULL (the default) trains it from the data (as ssm_plot_circle() does).
center: Optional. A single number giving the amplitude at the center of the circle (default = 0). Ring labels and the amplitude-to-radius mapping are guaranteed to agree.
r_axis_angle: Optional. A single number giving the displacement (in degrees) along which the amplitude (radial) axis and its labels are drawn. NULL (the default) places it automatically in the widest gap between the displacement spokes, so the amplitude labels never collide with a spoke label.
...: Reserved for future extensions; currently unused.

Details

coord_circumplex() subclasses ggplot2::coord_radial() and hard-pins the angular convention (displacement 0 at the right, increasing counterclockwise, the 0/360 range with no expansion) so the circumplex angle invariants survive the transform. The amplitude at the circle's center and at its outer ring are the radial limits, set once here.

Examples

Run this code

data("jz2017")
res <- ssm_analyze(jz2017, scales = 2:9, measures = "NARPD")
ggplot2::ggplot(res$results) +
  coord_circumplex(amax = 0.5) +
  geom_ssm_point(ggplot2::aes(amplitude = a_est, displacement = d_est))