The vocabulary for reshaping a finished atlas – dropping regions, gathering
views, boolean geometry between labels – lives in ggseg.formats, because it
belongs to the atlas format rather than to any one builder. Every atlas
build reaches for both packages, so ggseg.extra re-exports the verbs and
library(ggseg.extra) is enough.
Reading an atlas
atlas_regions(), atlas_labels(), atlas_views() and atlas_type()
report what an atlas holds. atlas_geom(), atlas_sf(),
atlas_polygons(), atlas_meshes(), atlas_vertices(),
atlas_palette() and atlas_geometry_type() reach into its parts.
Changing which regions are in it
atlas_region_remove() and atlas_region_keep() drop or select regions by
regex. atlas_region_rename() rewrites display names without touching
labels. atlas_region_contextual() keeps a region's geometry as a grey
outline but takes it out of the palette, which is how the brain silhouette
behind an atlas is made; atlas_context_remove() drops it again.
atlas_region_op() does boolean geometry between two labels, and
atlas_core_add() joins extra columns onto $core.
Changing which views are in it
atlas_view_keep(), atlas_view_remove() and atlas_view_reorder()
select and order the 2D views. atlas_view_remove_region() drops one
region from some views only, atlas_view_remove_small() drops slivers
below an area, and atlas_view_gather() closes the gaps between panels.
Building an atlas object
ggseg_atlas() is the constructor, and validates that core, palette and
geometry agree; is_ggseg_atlas() tests the result. Reach for them when
you have edited a component by hand and want it checked.
What is not re-exported
Only functions are. ggseg.formats also ships atlases named dk, aseg,
tracula and suit, and so does ggseg; attaching the whole namespace
would mask one set with the other depending on load order, which is a
silently wrong atlas rather than an error.
Four more verbs - atlas_centerlines(), atlas_plot_palette(),
atlas_structure_reorder() and atlas_view_select() - exist only in
ggseg.formats' development build, so re-exporting them here would stop this
package building against the release its DESCRIPTION asks for. They can come
across once ggseg.formats releases them and the floor here moves up.
See also
atlas_polish(), atlas_simplify(), atlas_smooth() and
atlas_dilate(), which shape an atlas's geometry and are native to
ggseg.extra.