ggbiplot: Biplot for Principal Components using ggplot2

In OceanTracer: Marine Source Unmixing Toolkit

Biplot for Principal Components using ggplot2

Description

Renders a custom publication-ready biplot for PCA models created via prcomp(), princomp(), FactoMineR::PCA(), or MASS::lda().

Usage

ggbiplot(
  pcobj,
  choices = 1:2,
  scale = 1,
  pc.biplot = TRUE,
  obs.scale = 1 - scale,
  var.scale = scale,
  groups = NULL,
  ellipse = FALSE,
  ellipse.prob = 0.68,
  labels = NULL,
  labels.size = 3,
  alpha = 1,
  var.axes = TRUE,
  circle = FALSE,
  circle.prob = 0.69,
  varname.size = 3,
  varname.adjust = 1.5,
  varname.abbrev = FALSE,
  ...
)

Arguments

pcobj	Object. A PCA object returned by prcomp, princomp, or PCA().
choices	Numeric vector of length 2. Indices of principal components to plot. Default c(1, 2).
scale	Numeric. Scale factor (0 or 1). Covariance biplot (scale = 1), form biplot (scale = 0). Default 1.
pc.biplot	Logical. If TRUE, ensures compatibility with biplot.princomp() scaling. Default TRUE.
obs.scale	Numeric. Scale factor applied to observations. Default 1 - scale.
var.scale	Numeric. Scale factor applied to variables. Default scale.
groups	Factor. Optional grouping variable to color-code observations. Default NULL.
ellipse	Logical. If TRUE, draws a normal concentration ellipse for each group. Default FALSE.
ellipse.prob	Numeric. Probability level for concentration ellipse size. Default 0.68.
labels	Character vector. Optional custom labels for observations. Default NULL.
labels.size	Numeric. Text size used for observation labels. Default 3.
alpha	Numeric [0, 1]. Transparency for points. Default 1.
var.axes	Logical. If TRUE, renders variable loading arrows. Default TRUE.
circle	Logical. If TRUE, draws a correlation circle. Default FALSE.
circle.prob	Numeric. Size of the correlation circle in Normal probability. Default 0.69.
varname.size	Numeric. Text size for variable names. Default 3.
varname.adjust	Numeric. Adjustment factor for variable name placement (\ge 1 moves text away from arrow). Default 1.5.
varname.abbrev	Logical. If TRUE, abbreviates variable names. Default FALSE.
...	Additional arguments passed to ggplot2.

Value

A ggplot object.

OceanTracer documentation built on Oct. 15, 2026, 5:09 p.m.