aes

Bind column names to visual channels to form an aesthetic mapping.

Aesthetic mappings tell plot how to turn data columns into visual properties: which column drives the x axis, which becomes a colour, etc. Pass the result as the mapping argument of plot or any geom layer.

Channel values can also be late-binding markers that defer resolution past the point where a column was first bound:

• Use from-theme to pull a scalar from the active theme.
• Use after-stat to substitute a column or closure result published by the layer’s stat.
• Use after-scale to post-transform a channel’s scale-resolved value just before draw.
• Use stage to compose all three lanes for a single channel.

Usage

aes(
  x: none,
  y: none,
  colour: none,
  fill: none,
  size: none,
  alpha: none,
  linewidth: none,
  group: none,
  shape: none,
  linetype: none,
  label: none,
  xmin: none,
  xmax: none,
  ymin: none,
  ymax: none,
  xend: none,
  yend: none,
  xintercept: none,
  yintercept: none,
  slope: none,
  intercept: none,
  weight: none,
  stroke: none,
  x0: none,
  y0: none,
  a: none,
  b: none,
  angle: none,
  radius: none,
  z: none,
)

Parameters

Parameter	Default	Description
x	none	Column name for the x position.
y	none	Column name for the y position.
colour	none	Column name driving the stroke colour.
fill	none	Column name driving the fill colour.
size	none	Column name driving marker or line size.
alpha	none	Column name driving opacity.
linewidth	none	Column name driving line stroke thickness.
group	none	Column name used to partition layers that connect observations.
shape	none	Column name driving marker shape.
linetype	none	Column name driving line dash pattern.
label	none	Column name used by geom-text and geom-label.
xmin	none	Column name for the lower x bound (ribbons, error bars).
xmax	none	Column name for the upper x bound.
ymin	none	Column name for the lower y bound.
ymax	none	Column name for the upper y bound.
xend	none	Column name for the x end point of a segment.
yend	none	Column name for the y end point of a segment.
xintercept	none	Column name or scalar for vertical reference lines.
yintercept	none	Column name or scalar for horizontal reference lines.
slope	none	Slope for oblique reference lines (@geom-abline).
intercept	none	Intercept for oblique reference lines.
weight	none	Column name carrying per-row statistical weights.
stroke	none	Column name driving marker outline thickness (@geom-point).
x0	none	Column name for the x centre of an ellipse (@geom-ellipse).
y0	none	Column name for the y centre of an ellipse.
a	none	Column name for the ellipse semi-major radius in data units.
b	none	Column name for the ellipse semi-minor radius in data units.
angle	none	Column name for the ellipse rotation in radians (@geom-ellipse) or the spoke direction in radians (@geom-spoke).
radius	none	Column name for the spoke length in data units (@geom-spoke).
z	none	Column name for the value summarised over a 2D grid (stat-summary-2d, @stat-summary-hex).

Returns

Dictionary tagged kind: "aes", consumed by plot and geom layers.

Examples

Bind three columns: x, y, and a categorical colour.

#let iris = (
  (x: 5.1, y: 3.5, sp: "setosa"),
  (x: 7.0, y: 3.2, sp: "versicolor"),
  (x: 6.3, y: 3.3, sp: "virginica"),
)
#plot(
  data: iris,
  mapping: aes(x: "x", y: "y", colour: "sp"),
  layers: (geom-point(size: 3pt),),
  width: 10cm,
  height: 6cm,
)

Bind ribbon endpoints (ymin, ymax) alongside a centre line, sharing the same x between the two layers.

#let d = range(0, 10).map(i => (
  x: i, y: i * 0.5, lo: i * 0.5 - 0.6, hi: i * 0.5 + 0.6,
))
#plot(
  data: d,
  mapping: aes(x: "x", y: "y", ymin: "lo", ymax: "hi"),
  layers: (
    geom-ribbon(alpha: 0.3),
    geom-line(stroke: 1pt),
  ),
  width: 10cm,
  height: 6cm,
)

Bind y to the count column the stat publishes via after-stat.

#let d = ((grp: "a"), (grp: "b"), (grp: "a"), (grp: "c"))
#plot(
  data: d,
  mapping: aes(x: "grp", y: after-stat("_count"), fill: "grp"),
  layers: (geom-bar(),),
  width: 10cm,
  height: 6cm,
)

Darken the marker outline from the trained fill palette via after-scale.

#let d = ((x: 1, sp: "a"), (x: 2, sp: "b"), (x: 3, sp: "a"))
#plot(
  data: d,
  mapping: aes(
    x: "x",
    y: "x",
    fill: "sp",
    colour: stage(
      start: "sp",
      after-scale: (c, _) => c.darken(40%),
    ),
  ),
  layers: (geom-point(size: 4pt, stroke: 0.6pt),),
  width: 10cm,
  height: 6cm,
)

See also

plot, geom-point, as-factor, from-theme, after-stat, after-scale, stage.