geom-density-2d-filled

Filled 2D density layer: shaded bands of the estimated (x, y) density.

Mapping must provide x and y; the layer accepts raw observations, no pre-computed grid is needed. The stat binds fill to the band’s density level, so a continuous fill scale shades by height.

Usage

geom-density-2d-filled(
  mapping: none,
  data: none,
  bw: auto,
  adjust: 1,
  n: 25,
  bins: 10,
  binwidth: none,
  breaks: auto,
  colour: auto,
  fill: auto,
  stroke: none,
  alpha: auto,
  stat: auto,
  position: "identity",
  key: auto,
  inherit-aes: true,
)

Parameters

Parameter	Default	Description
mapping	none	Layer-specific aesthetic mapping built with aes. Must map x and y.
data	none	Layer-specific dataset, or a function applied to the plot data returning the layer frame. Falls back to the plot data when none.
bw	auto	Kernel standard deviation per axis. auto derives it per axis from R’s bw.nrd / 4; pass a number for both axes or an (x, y) tuple.
adjust	1	Bandwidth multiplier: adjust: 0.5 halves the smoothing.
n	25	Density grid resolution per axis: a number or an (x, y) tuple.
bins	10	Target band count when breaks and binwidth are unset.
binwidth	none	Fixed step between band edges. Overrides bins.
breaks	auto	Explicit array of band edges. Overrides bins and binwidth.
colour	auto	Fixed polygon outline colour. auto resolves via the colour scale.
fill	auto	Fixed band fill. auto shades by density level through the fill scale.
stroke	none	Outline thickness (a Typst length); none (default) keeps the per-cell tiling seamless.
alpha	auto	Fill opacity in [0, 1].
stat	auto	Statistical transform. auto builds stat-density-2d-filled from the parameters above; pass a stat name or stat object to override.
position	"identity"	Position adjustment name. Usually "identity".
key	auto	Legend glyph override built with a draw-key-* helper. auto picks the default for the geom.
inherit-aes	true	Whether to merge the plot-level mapping into this layer’s mapping.

Returns

Layer dictionary consumed by plot.

Examples

Shaded density bands of two point clouds.

#let d = range(0, 60).map(i => {
  let lobe = calc.rem(i, 2)
  (
    x: 2 + lobe * 4 + calc.sin(i * 1.7) * 0.8,
    y: 2 + lobe * 3 + calc.cos(i * 2.3) * 0.8,
  )
})
#plot(
  data: d,
  mapping: aes(x: "x", y: "y"),
  layers: (geom-density-2d-filled(),),
  scales: scales(
    x: scale-continuous(expand: (0,0)),
    y: scale-continuous(expand: (0,0)),
  ),
  width: 10cm,
  height: 6cm,
)

See also

stat-density-2d-filled, geom-density-2d, geom-contour-filled.