Copyright	(C) 2010-2015 Maximilian Bolingbroke
License	BSD-3-Clause (see the file LICENSE)
Maintainer	Oleg Grenrus <oleg.grenrus@iki.fi>
Safe Haskell	Safe
Language	Haskell98

Text.EditDistance

Description

Computing the edit distances between strings

Synopsis

data Costs a
- = ConstantCost !Int
- | VariableCost (a -> Int)
data EditCosts = EditCosts {
- deletionCosts :: Costs Char
- insertionCosts :: Costs Char
- substitutionCosts :: Costs (Char, Char)
- transpositionCosts :: Costs (Char, Char)
}
defaultEditCosts :: EditCosts
levenshteinDistance :: EditCosts -> String -> String -> Int
restrictedDamerauLevenshteinDistance :: EditCosts -> String -> String -> Int

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.