rownames and colnames respectively).distUnion(...)match_on, exactMatch, or other distance
creation function).distUnion(A, B)
will favor entries in A over entries in B).rbind provides
a way to combine the different objects. Likewise,
cbind provides a way to combine distance
specifications over common treated units, but different control
units.distUnion can combine distance units that have common
treated and control units into a coherent single distance
object. If there are duplicate treated-control entries in multiple
input distances, the first entry will be used.
match_on, exactMatch,
fullmatch, pairmatch,
cbind, rbind