levenshtein package:edit-distance

Find the Levenshtein edit distance between two strings. That is to say, the number of deletion, insertion and substitution operations that are required to make the two strings equal. Note that this algorithm therefore does not make use of the transpositionCost field of the costs. See also: http://en.wikipedia.org/wiki/Levenshtein_distance.

Find the "restricted" Damerau-Levenshtein edit distance between two strings. This algorithm calculates the cost of the so-called optimal string alignment, which does not always equal the appropriate edit distance. The cost of the optimal string alignment is the number of edit operations needed to make the input strings equal under the condition that no substring is edited more than once. See also: http://en.wikipedia.org/wiki/Damerau-Levenshtein_distance.