Convert between a vellumplot spec and a Vega-Lite specification

spec_to_vegalite() translates a PlotSpec into a Vega-Lite specification; spec_from_vegalite() translates one back. Both are layered grammars of graphics, so the mapping is direct for the common cases — marks, encodings, scales (domain / log-sqrt type / categorical range / title), bin + count, faceting, inline data, and the plot title.

Usage

spec_to_vegalite(plot, json = FALSE)

spec_from_vegalite(vl, data = NULL, env = globalenv())

Arguments

plot

A PlotSpec.

json

For spec_to_vegalite(), return a JSON string instead of a list.

vl

A Vega-Lite spec as a parsed list or a JSON string.

data

Optional data frame for a Vega-Lite spec whose data is external.

env

Environment channel expressions are re-quoted in (for spec_from_vegalite()).

Value

spec_to_vegalite() returns a Vega-Lite spec (a list, or JSON string if json = TRUE); spec_from_vegalite() returns a PlotSpec.

Details

The bridge covers a documented subset (see the "Specs, agents, and interoperability" article). Anything it cannot map — polar/flipped coordinates, layer effects, patterns, statistical marks without a Vega-Lite equivalent — is reported via a warning listing the dropped features, never silently diverged.

See also

as_spec(), spec_to_json()

Examples

p <- vplot(mtcars) |> mark_point(x = wt, y = mpg, color = cyl)
vl <- spec_to_vegalite(p)
vl$mark
#> $type
#> [1] "point"
#>