scale-colour-discrete

Discrete colour scale mapping categorical levels to stroke colours.

Usage

scale-colour-discrete(
  name,
  palette,
  limits,
  oob,
  labels,
)

Parameters

Parameter	Default	Description
name		Legend title. Overrides any name set via labels when both are present.
palette		Colour source: an array of colours, or auto.
limits		Array of level names controlling order and inclusion, or none.
oob		Out-of-range policy: "drop" (default) removes rows whose value falls outside limits; "squish" clamps continuous values to the nearest endpoint.
labels		Array of legend labels aligned with limits, or auto.

Returns

Scale object consumed by plot.

Examples

Default palette mapping three categories to the library’s eight reserved discrete colours.

#let d = (
  (x: 1, y: 2, sp: "a"),
  (x: 2, y: 4, sp: "b"),
  (x: 3, y: 3, sp: "c"),
)
#plot(
  data: d,
  mapping: aes(x: "x", y: "y", colour: "sp"),
  layers: (geom-point(size: 3pt),),
  scales: (scale-colour-discrete(),),
  width: 10cm,
  height: 6cm,
)

Override palette with an explicit colour array to hand-pick the mapping order.

#let d = (
  (x: 1, y: 2, sp: "a"),
  (x: 2, y: 4, sp: "b"),
  (x: 3, y: 3, sp: "c"),
)
#plot(
  data: d,
  mapping: aes(x: "x", y: "y", colour: "sp"),
  layers: (geom-point(size: 3pt),),
  scales: (scale-colour-discrete(palette: (
    rgb("#1b9e77"), rgb("#d95f02"), rgb("#7570b3"),
  )),),
  width: 10cm,
  height: 6cm,
)

Bind a colour-blind-friendly palette to penguin species and reorder the legend via limits.

#plot(
  data: penguins,
  mapping: aes(x: "flipper-len", y: "body-mass", colour: "species"),
  layers: (geom-point(size: 2pt, alpha: 0.85),),
  scales: (scale-colour-discrete(
    palette: (rgb("#0072B2"), rgb("#D55E00"), rgb("#009E73")),
    limits: ("Adelie", "Chinstrap", "Gentoo"),
  ),),
  labels: labels(x: "Flipper Length (mm)", y: "Body Mass (g)", colour: "Species"),
  width: 11cm,
  height: 6cm,
)

See also

scale-colour-manual, scale-colour-viridis-d, scale-fill-discrete.