Extract sf geometries from ggplot_build layer data as GeoJSON strings

Extracts the sfc geometry column from a data.frame produced by ggplot_build()$data[[i]], normalizes CRS to WGS84 unconditionally (per D-11), and serializes each geometry as a GeoJSON geometry string via geojsonsf::sfc_geojson() (per D-10).

Usage

extract_sf_geometries(df)

Arguments

df

A data.frame from ggplot_build()$data[[i]] containing an sfc column

Value

Character vector of GeoJSON geometry strings, one per row

Details

gg2d3's public sf renderer accepts polygon, point, and line geometry families for geom_sf() and projected-anchor annotation support for geom_sf_text() and geom_sf_label(). Missing CRS emits "geom_sf layer has missing CRS; coordinates will be serialized as-is". Unsupported, empty, invalid, or missing geometries emit "geom_sf layer skipped %d unsupported, empty, invalid, or missing geometries" and are skipped before rendering.