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Colour scales

Source: R/scales.R
scale_color_continuous.Rd

Declare a colour scale for the color/fill channel. Continuous data get a perceptual ramp; discrete data get a qualitative palette. scale_*_manual() sets exact colours, scale_*_gradient() a two-point ramp, and scale_*_gradient2() a diverging three-point ramp (low–mid–high) centred on midpoint — for signed or anomaly data where a meaningful zero should sit at the neutral colour. The fill variants are identical (colour and fill share one scale). A legend is drawn automatically when colour is mapped.

Usage

scale_color_continuous(
  plot,
  palette = NULL,
  limits = NULL,
  breaks = NULL,
  labels = NULL,
  name = NULL
)

scale_color_discrete(
  plot,
  palette = NULL,
  breaks = NULL,
  labels = NULL,
  name = NULL
)

scale_color_manual(plot, values, name = NULL)

scale_color_gradient(plot, low = "#132B43", high = "#56B1F7", name = NULL)

scale_color_gradient2(
  plot,
  low = "#832424",
  mid = "#FFFFFF",
  high = "#3A3A98",
  midpoint = 0,
  name = NULL
)

scale_fill_continuous(
  plot,
  palette = NULL,
  limits = NULL,
  breaks = NULL,
  labels = NULL,
  name = NULL
)

scale_color_gradientn(plot, colours, name = NULL)

scale_fill_gradientn(plot, colours, name = NULL)

scale_colour_gradientn(plot, colours, name = NULL)

scale_fill_discrete(
  plot,
  palette = NULL,
  breaks = NULL,
  labels = NULL,
  name = NULL
)

scale_fill_manual(plot, values, name = NULL)

scale_fill_gradient(plot, low = "#132B43", high = "#56B1F7", name = NULL)

scale_fill_gradient2(
  plot,
  low = "#832424",
  mid = "#FFFFFF",
  high = "#3A3A98",
  midpoint = 0,
  name = NULL
)

scale_colour_continuous(
  plot,
  palette = NULL,
  limits = NULL,
  breaks = NULL,
  labels = NULL,
  name = NULL
)

scale_colour_discrete(
  plot,
  palette = NULL,
  breaks = NULL,
  labels = NULL,
  name = NULL
)

scale_colour_manual(plot, values, name = NULL)

scale_colour_gradient(plot, low = "#132B43", high = "#56B1F7", name = NULL)

scale_colour_gradient2(
  plot,
  low = "#832424",
  mid = "#FFFFFF",
  high = "#3A3A98",
  midpoint = 0,
  name = NULL
)

Arguments

plot

A PlotSpec.

palette

A vector of colours, or a single palette name passed to grDevices::hcl.colors() (e.g. "Batlow", "Blues", "Set 2"; matched case/space-insensitively). NULL uses a sensible default.

limits

For the continuous colour scales, a length-2 numeric c(min, max) fixing the mapped data range (the direct form of lims(color = ...)).

breaks, labels

Explicit legend breaks / labels, or NULL.

name

Legend title, or NULL to derive from the encoding.

values

For scale_*_manual(), a vector of colours; if named, matched to data levels by name (unmatched levels draw grey).

low, high

For scale_*_gradient()/scale_*_gradient2(), the endpoint colours.

mid

For scale_*_gradient2(), the midpoint colour.

midpoint

For scale_*_gradient2(), the data value placed at mid (default 0); values above and below diverge to high and low.

colours

For scale_*_gradientn(), an n-stop vector of colours the continuous ramp interpolates through.

Value

The modified PlotSpec.

Details

Continuous and binned ramps built from a plain colour vector are interpolated in the perceptually-uniform Oklab space, so they avoid the muddy, over-dark midtones and hue drift of sRGB blending. Designed perceptual palettes (the default, and hcl.colors() names) are already uniform and unaffected. Set options(vellumplot.color.interpolation = "srgb") (or "lab") to change the blend space globally.

Examples

vplot(mtcars) |>
  mark_point(x = wt, y = mpg, color = hp) |>
  scale_color_continuous(palette = "Batlow")