as_polygon_atlas: Convert a ggseg atlas to the sf-optional polygon...

In ggseg.formats: Brain Atlas Data Structures for the 'ggsegverse' Ecosystem

Convert a ggseg atlas to the sf-optional polygon representation

Description

Sets the single geom slot to the brain_polygons representation, converting from sf if needed. The result renders identically via the geom_polygon-based path in ggseg, but no longer depends on the sf class machinery in ⁠$data⁠ — useful for wasm builds and air-gapped installs.

Usage

as_polygon_atlas(atlas)

Arguments

atlas

A ggseg_atlas (or legacy brain_atlas) object.

Details

Conversion is lossless, so a single representation is kept (no redundant sf alongside polygons). To rehydrate sf for geometric operations later, use as_sf_atlas().

This doubles as the backward-compatible path for sf-optional installs: a lite-only ggseg that meets a still-sf-backed atlas converts it on the fly when sf is installed. When sf is not installed the geometry cannot be read, so the call aborts with a pointer to migrate_atlas_files() — which the atlas maintainer runs once (on a machine with sf) to ship the package in the polygon format.

Value

A ggseg_atlas whose ⁠$data$geom⁠ is a brain_polygons object.

Examples

## Not run: 
poly <- as_polygon_atlas(dk())
is_atlas_polygon(poly) # TRUE

## End(Not run)

ggseg.formats documentation built on July 2, 2026, 5:07 p.m.