edits (rubygems):     Edit distance algorithms including Levenshtein,     Restricted Edit (Optimal Alignment) and Damerau-Levenshtein distances,     and Jaro & Jaro-Winkler similarity. 
Keywords: damerau-levenshtein|edit-distance|edit-distance-algorithm|fuzzy-matching|jaro|jaro-winkler|levenshtein|restricted-edit|ruby|similarity-measures|text