blank

Creates invisible positioning guides. Use blank when you need to define positions for other marks (like line or ribbon) without rendering visible shapes.

const locations = Object.entries(lakeLocations).map(([lake, { x, y }]) => ({
  lake,
  x,
  y,
}));

gf.layer([
  gf
    .chart(locations)
    .flow(gf.scatter({ by: "lake", x: "x", y: "y" }))
    .mark(gf.blank().name("points")),
  gf
    .chart(gf.selectAll("points"))
    .mark(gf.line({ stroke: "steelblue", strokeWidth: 2 })),
]).render(root, { w: 400, h: 250, axes: true });

Signature

blank({ w?, h?, fill?, stroke?, strokeWidth?, rx?, ry?, debug? })

Parameters

Option	Type	Description
w	number | string | Value<number> | FieldExpr	Width — same channel-value shapes as a leaf mark's "size" channel (e.g. rect's w): a number for fixed, a field name to encode data, or a field(...) pipeline like field("count").sum() for an aggregate (default 0)
h	number | string | Value<number> | FieldExpr	Height — same shapes as w (default 0)
fill	string	Fill color (invisible by default)
stroke	string	Stroke color
strokeWidth	number	Stroke width
rx	number	Horizontal border radius
ry	number	Vertical border radius
debug	boolean	When true, renders visibly for debugging

Examples

// Create invisible anchor points for a line chart
.mark(blank().name("points"))

// Blank with height encoding for area charts
.mark(blank({ h: "value" }).name("bars"))

// Debug mode to see blank positions
.mark(blank({ debug: true }).name("guides"))