Alpha (opacity) scale — scale_alpha • vellumplot

Declare the scale for a mapped alpha aesthetic: data values map to an opacity range in [0, 1]. An alpha legend is drawn automatically.

Usage

scale_alpha(plot, range = NULL, limits = NULL, breaks = NULL, name = NULL)

scale_alpha_continuous(
  plot,
  range = NULL,
  limits = NULL,
  breaks = NULL,
  name = NULL
)

Arguments

plot: A PlotSpec.
range: Numeric length-2 output opacity range, or NULL for the default c(0.1, 1).
limits: Numeric length-2 data domain, or NULL to train from the data.
breaks: Explicit legend breaks, or NULL.
name: Legend title, or NULL to derive from the encoding.

Value

The modified PlotSpec.

Examples

vplot(mtcars) |> mark_point(x = wt, y = mpg, alpha = hp) |> scale_alpha(range = c(0.2, 1))