scale-alpha-binned
Binned continuous alpha scale.
Maps a numeric column onto an opacity range, but groups values into n-breaks bins for the legend. The mapping stays continuous; only the legend swatches snap to bin centres.
Usage
scale-alpha-binned(
n-breaks: 4,
breaks: auto,
range: (0.1, 1),
name: none,
limits: none,
oob: "drop",
labels: auto,
)Parameters
| Parameter | Default | Description |
|---|---|---|
n-breaks |
4 |
Number of legend bins. Ignored when breaks is set. |
breaks |
auto |
Array of bin edges for the legend, or auto to derive equal-width bins from n-breaks. Affects the legend only; the per-row mapping stays continuous. |
range |
(0.1, 1) |
Pair (min, max) bounding the output opacity in [0, 1]. |
name |
none |
Legend title. Overrides any name set via labels when both are present. |
limits |
none |
Pair (lo, hi) clipping the trained domain, or none. |
oob |
"drop" |
Out-of-range policy: "drop" (default) removes rows whose value falls outside limits; "squish" clamps continuous values to the nearest endpoint. |
labels |
auto |
Array of legend labels aligned with breaks, or auto. |
Returns
Scale object consumed by plot.
Examples
Opacity binned into four legend swatches.
#let d = range(0, 10).map(i => (x: i, y: i, w: i + 1))
#plot(
data: d,
mapping: aes(x: "x", y: "y", alpha: "w"),
layers: (geom-point(size: 4pt, fill: rgb("#1f77b4")),),
scales: (scale-alpha-binned(n-breaks: 4, range: (0.2, 1)),),
width: 10cm,
height: 6cm,
)
