Text.EditDistance

Computing the edit distances between strings

Documentation

data Costs a

Constructors

ConstantCost !Int

VariableCost (a -> Int)

data EditCosts

Constructors

EditCosts

Fields

deletionCosts :: Costs Char

Cost of deleting the specified character from the left string

insertionCosts :: Costs Char

Cost of inserting the specified characters into the right string

substitutionCosts :: Costs (Char, Char)

Cost of substituting a character from the left string with one from the right string -- with arguments in that order.

transpositionCosts :: Costs (Char, Char)

Cost of moving one character backwards and the other forwards -- with arguments in that order.

defaultEditCosts :: EditCosts

levenshteinDistance :: EditCosts -> String -> String -> Int

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.

restrictedDamerauLevenshteinDistance :: EditCosts -> String -> String -> Int

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.