plotlsirm (version 0.1.3)

radarplot: Radar plot of branch-specific abilities (single or multiple subjects)

Description

Draws a radar / spider chart in which each axis ("branch") represents a domain-specific ability and the radial extent marks the attained score. Single-subject mode shades the overall-ability circle and fills the polygon formed by the branch scores. Multi-subject mode overlays several polygons on a common background, optionally coloring, labelling, and annotating each subject.

Usage

radarplot(
  data = NULL,
  labels,
  max_radius = 100,
  branch_max = 10,
  overallAbility = NA,
  ability_range = c(-3, 3),
  abilityCutoffs = c(-1.68, 1.68),
  bgColors = c("red", "yellow", "green"),
  markerInd = NULL,
  point_cex = 4,
  subjectLabels = NULL,
  sampleColors = NULL,
  showOverallAbility = FALSE,
  title = NULL,
  plot_margin = margin(t = 20, r = 20, b = 20, l = 20),
  label_angle_offset = 0
)

Value

A ggplot object representing the radar chart (also printed as a side effect).

Arguments

data

Numeric vector (one subject) or matrix/data-frame (\(m \times n\)) of scores, where \(n\) = length(labels) is the number of branches. Rows correspond to subjects when data is two-dimensional.

labels

Character vector of length \(n\) giving the label for each branch / axis.

max_radius

Numeric. Maximum drawing radius in plot units after the scores in ability_range have been linearly rescaled. Default 100.

branch_max

Numeric. Reserved for future branch-specific scaling. Currently ignored.

overallAbility

Numeric scalar or length-\(m\) vector giving the overall ability for each subject. Used to set the radius of the shaded background circle for that subject. If NA the maximum of ability_range is used.

ability_range

Numeric length-2 vector [min, max] defining the scale of the input scores. These limits are mapped to the interval [0, max_radius].

abilityCutoffs

Numeric. Reserved for future color gradations; not used in the current version.

bgColors

Character vector of colors for the shaded background circles. Only the first element is used at present.

markerInd

Numeric vector (0 = hollow, 1 = solid) of length \(n\) indicating the point style for each branch. When data is a matrix this can be supplied as an \(m \times n\) matrix so each subject has its own marker pattern.

point_cex

Numeric point size for branch markers. Default 4.

subjectLabels

Optional character vector of length \(m\) naming each subject in multi-subject mode. Row names of data are used when available; otherwise "Subject 1", "Subject 2", ... are generated.

sampleColors

Character vector of length \(m\) giving the polygon/point color for each subject. Defaults to a distinct hue palette if NULL.

showOverallAbility

Logical. If TRUE, prints each subject's overall ability beneath their label.

title

Optional plot title.

plot_margin

A ggplot2::margin() object controlling the outer whitespace around the figure. Default adds 20 pt on every side.

label_angle_offset

Numeric scalar or length-\(n\) vector specifying (in degrees) how much to rotate each branch label relative to its default tangential orientation. Useful for fine-tuning readability.

Examples

## Single subject -------------------------------------------------
#### the distance from a person to all items/item clusters
dist_z_w <- c(item1 = 1.6, item2 = 0.8, item3 = 1.9, item4 = 2.5, item5 = 0.4)
#### transform distance to strength
strength <- exp(-dist_z_w)
#### plot the radar
radarplot(strength, labels = names(strength),
          overallAbility = 1.8, showOverallAbility = TRUE,
          title = "Student A profile")

## Multiple subjects ---------------------------------------------
set.seed(1)
#### strength for 3 persons on 5 items
dat <- matrix(rnorm(15, 3, 1), nrow = 3,
              dimnames = list(NULL, c("item1", "item2", "item3", "item4", "item5")))
radarplot(dat, labels = colnames(dat),
          overallAbility = c(-1.8, 0.5, 2.5),
          subjectLabels  = c("Alice", "Bob", "Cara"),
          sampleColors   = c("#1b9e77", "#d95f02", "#7570b3"),
          showOverallAbility = TRUE,
          title = "Class-level comparison")