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Ridge Plot (Stacked Density Plot)

Source: R/plotRidge.R
plotRidge.Rd

Draws stacked kernel density estimates (ridge plot) for grouped data. Each group is displayed as a density curve shifted along the y-axis.

Usage

# Default S3 method
plotRidge(
  x,
  ...,
  add = FALSE,
  bw = "nrd0",
  scale = 1,
  spacing = 1,
  col = NULL,
  border = NULL,
  lwd = 1,
  lty = 1,
  fill = TRUE,
  grid = NA,
  main = "",
  xlab = "",
  ylab = "",
  xlim = NULL,
  ylim = NULL
)

# S3 method for class 'formula'
plotRidge(
  formula,
  data = NULL,
  subset,
  na.action = na.omit,
  ...,
  add = FALSE,
  bw = "nrd0",
  scale = 1,
  spacing = 1,
  col = NULL,
  border = NULL,
  lwd = 1,
  lty = 1,
  fill = TRUE,
  grid = NA,
  main = "",
  xlab = "",
  ylab = "",
  xlim = NULL,
  ylim = NULL
)

Arguments

x

A numeric vector, or a list of numeric vectors representing groups.

...

additional graphical parameters passed to par().

add

logical; if TRUE, adds to an existing plot.

bw

bandwidth for stats::density().

scale

scaling factor for density height.

spacing

vertical spacing between ridges.

col

fill color(s).

border

border color(s).

lwd

line width(s).

lty

line type(s).

fill

logical; fill area under densities.

grid

logical, NA, or list controlling grid.

main, xlab, ylab

plot labels.

xlim, ylim

axis limits.

formula

A formula of the form y ~ group.

data

optional data frame.

subset

optional subset expression.

na.action

function to handle missing values.

Value

Invisibly returns NULL.

Details

Ridge plots are useful for comparing distributions across multiple groups. Each density is normalized and vertically offset, improving readability compared to overlaid density plots.

See also

plotDens()

Examples

set.seed(1)
df <- data.frame(
  value = c(rnorm(100), rnorm(100, 2), rnorm(100, 4)),
  group = rep(c("A", "B", "C"), each = 100)
)

plotRidge(value ~ group, data = df)