ggaction 0.0.5

Point Appearance

Cars scatterplot with grouped regression lines and confidence bands
Layered points, derived fits, and confidence bands.

encodeRadius({ value, target? })

Broadcast a non-negative finite graphical radius to a point mark.

program.encodeRadius({ value: 3 });

encodePointRadius({ value, target? }) is the preferred alias in Polar charts. It records encodeRadius as a wrapped child and remains distinct from encodeR, which assigns semantic radial position.

Option Type Default
value non-negative finite number required
target point mark ID current mark

Radius is fixed appearance. It does not create a semantic field encoding and is not a Polar radial position channel.

Point field encodings

program
  .encodeSize({ field: "Acceleration" })
  .encodeShape({ field: "Origin" })
  .encodeOpacity({ value: 0.27 });

encodeSize({ field, target?, fieldType?, scale? }) requires a quantitative field. Its scale accepts id, type, domain, and an area range; automatic range is [24, 196]. Circles use sqrt(area / PI) as radius and squares use sqrt(area) as side length, so the two shapes represent equal visual area.

encodeShape({ field, target?, fieldType?, scale? }) requires a nominal field. Its ordinal scale accepts the 12 shared point shapes documented under Marks. The automatic range uses each shape once and rejects more than 12 distinct categories rather than silently repeating symbols. Explicit ranges must contain unique supported shapes. Mixed circle, rect, and Z-closed path symbols are stored as typed items in one graphical collection.

encodeOpacity accepts exactly one of value or field. A constant value from 0 to 1 is graphical. A quantitative field creates semantic opacity and a linear scale with automatic range [0.2, 1]; its scale supports explicit domain/range plus nice, zero, clamp, and reverse. Calling the action again atomically replaces constant↔field or field↔field mode. Every resolved opacity remains concrete in graphicSpec.

All point appearance actions invoke the same point materializer. Existing x, y, color, size, shape, and opacity state is recombined after each change and after Canvas bounds change, making action order irrelevant.

Calling encodeSize or encodeShape again replaces its existing field and compatible scale binding. Omitting scale.id reuses the current scale; providing a new ID retains the previous named scale. Existing legends are recomputed, inferred legend titles follow the new field, and explicit legend titles and styles remain unchanged.

Appearance overview · Point marks · Legends