agrep: only return best match(es)

The agrep package uses Levenshtein Distances to match strings. The package RecordLinkage has a C function to calculate the Levenshtein Distance, which can be used directly to speed up your computation. Here is a reworked ClosestMatch function that is around 10x faster

library(RecordLinkage)

ClosestMatch2 = function(string, stringVector){

  distance = levenshteinSim(string, stringVector);
  stringVector[distance == max(distance)]

}

RecordLinkage package was removed from CRAN, use stringdist instead:

library(stringdist)

ClosestMatch2 = function(string, stringVector){

  stringVector[amatch(string, stringVector, maxDist=Inf)]

}