Marks

The mark represents the graphical mark of the visualization. Draco uses an encoding based on the Grammar of Graphics (GoG) [Wil12]. In the GoG, marks are described as Geometric objects (“geoms” for short). We use the term mark as that’s the term Vega-Lite [SMWH16] uses.

Marks have encodings, which define how data fields map to the mark’s visual properties.

If a view has multiple marks, Draco assumes that the marks are layered (i.e. they are in the same view space in the chart).

Mark Properties

(mark,type) : The mark type. One of point, bar, line, area, text, tick, or rect.

Example

entity(view,root,v).

entity(mark,v,m).
attribute((mark,type),m,tick).
entity(encoding,m,e).