Ternary Plot

Draws a ternary plot for compositional data consisting of three non-negative components per observation. Each row is interpreted as a composition and internally rescaled to sum to 1 if necessary.

Usage

plotTernary(
  x,
  y = NULL,
  z = NULL,
  ...,
  add = FALSE,
  col = NULL,
  pch = 16,
  cex = 1,
  grid = NA,
  lbl = NULL,
  main = "",
  xlim = c(-1, 1),
  ylim = c(-0.5, 1)
)

Arguments

x

A numeric vector, matrix, or data frame. If y and z are provided, x, y, and z are combined into a matrix. Otherwise, x must contain exactly three columns.

y

optional numeric vector for the second component.

z

optional numeric vector for the third component.

...

additional graphical parameters passed to par().

add

logical; if TRUE, adds to an existing plot.

col

point color(s).

pch

plotting symbol.

cex

point size.

grid

logical, NA, or list controlling the ternary grid.

lbl

character vector of length 3 specifying axis labels.

main

plot title.

xlim, ylim

plot limits (usually left at defaults).

Value

Invisibly returns NULL.

Details

A ternary plot represents three-part compositions on an equilateral triangle. Each observation \((x_1, x_2, x_3)\) is mapped to 2D coordinates using barycentric transformation. If rows do not sum to 1, they are automatically normalized with a warning.

Graphical elements such as grids are controlled via the unified plot design system using bedrock::callIf() and .theme().

See also

plotDens(), plotRidge()

Other plot.special: plotBinaryTree(), plotCirc(), plotLift(), plotMiss(), plotPolar(), plotPropCI(), plotTimeSeries(), plotTreemap(), plotWeb()

Examples

set.seed(1)
x <- runif(100)
y <- runif(100)
z <- runif(100)

plotTernary(x, y, z)
#> Warning: rows are rescaled to sum to 1


# matrix input
M <- cbind(x, y, z)
plotTernary(M, lbl = c("A", "B", "C"))
#> Warning: rows are rescaled to sum to 1