This function matches territorial units with a list of known units to derive the administrative hierarchy ID.
matchUnits(input = NULL, source = NULL, verbose = FALSE)[data.frame(1)] table in which to match administrative
units.
[integerish(1)] the geometry ID (geoID) from
which the terms have been taken.
[logical(1)] be verbose about what is happening
(default FALSE).
The table provided in input, where the given columns are
replaced by the column ahID, which contains the administrative
hierarchy ID.
names(input) must contain at least the al1 = ... to
match at least a certain nation. Further administrative levels are denoted
by column names al2, al3, ...