scale-colour-gradient2

Continuous diverging colour gradient through a midpoint.

Interpolates low to mid for values at or below midpoint, and mid to high for values at or above it.

Usage

scale-colour-gradient2(
  low,
  mid,
  high,
  midpoint,
  name,
  limits,
  oob,
  breaks,
  labels,
)

Parameters

Parameter	Default	Description
low		Colour for values far below midpoint.
mid		Colour at midpoint.
high		Colour for values far above midpoint.
midpoint		Value at which the palette transitions through mid.
name		Legend title. Overrides any name set via labels when both are present.
limits		Pair (lo, hi) clipping the trained domain, or none.
oob		Out-of-range policy: "drop" (default) removes rows whose value falls outside limits; "squish" clamps continuous values to the nearest endpoint.
breaks		Array of break values for the legend, or auto.
labels		Array of legend labels aligned with breaks, or auto.

Returns

Scale object consumed by plot.

Examples

Default diverging ramp pivoting at zero, useful for signed numeric values.

#let d = range(-5, 6).map(i => (x: i, y: i, z: i))
#plot(
  data: d,
  mapping: aes(x: "x", y: "y", colour: "z"),
  layers: (geom-point(size: 3pt),),
  scales: (scale-colour-gradient2(midpoint: 0),),
  width: 10cm,
  height: 6cm,
)

Shift midpoint to centre the ramp around a non-zero baseline.

#let d = range(0, 11).map(i => (x: i, y: i, z: i))
#plot(
  data: d,
  mapping: aes(x: "x", y: "y", colour: "z"),
  layers: (geom-point(size: 3pt),),
  scales: (scale-colour-gradient2(
    low: rgb("#1a9850"),
    mid: rgb("#ffffbf"),
    high: rgb("#d73027"),
    midpoint: 5,
  ),),
  width: 10cm,
  height: 6cm,
)

See also

scale-colour-gradient, scale-colour-gradientn, scale-fill-gradient2.