Load the currently active ontology
adb_ontology(..., type = "ontology")combination of column name in the ontology and value to filter
that column by to build a tree of the concepts nested into it; see
make_tree.
character(1)
the type of ontology to load,
either "ontology" to get the thematic concepts, or
"gazetteer" to get the territories.
returns a tidy table of an ontology or gazetteer that is used in an areal database.