org.projectodd.vdx.core.thirdparty

Class Levenshtein

java.lang.Object

org.projectodd.vdx.core.thirdparty.Levenshtein

public class Levenshtein
extends Object

Constructor Summary

Constructors

Constructor and Description
Levenshtein()

Method Summary

Modifier and Type	Method and Description
static int	getLevenshteinDistance(CharSequence s, CharSequence t, int threshold) Find the Levenshtein distance between two Strings if it's less than or equal to a given threshold.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

Levenshtein

public Levenshtein()

Method Detail

getLevenshteinDistance

public static int getLevenshteinDistance(CharSequence s,
                                         CharSequence t,
                                         int threshold)

Find the Levenshtein distance between two Strings if it's less than or equal to a given threshold.

This is the number of changes needed to change one String into another, where each change is a single character modification (deletion, insertion or substitution).

This implementation follows from Algorithms on Strings, Trees and Sequences by Dan Gusfield and Chas Emerick's implementation of the Levenshtein distance algorithm from http://www.merriampark.com/ld.htm

 StringUtils.getLevenshteinDistance(null, *, *)             = IllegalArgumentException
 StringUtils.getLevenshteinDistance(*, null, *)             = IllegalArgumentException
 StringUtils.getLevenshteinDistance(*, *, -1)               = IllegalArgumentException
 StringUtils.getLevenshteinDistance("","", 0)               = 0
 StringUtils.getLevenshteinDistance("aaapppp", "", 8)       = 7
 StringUtils.getLevenshteinDistance("aaapppp", "", 7)       = 7
 StringUtils.getLevenshteinDistance("aaapppp", "", 6))      = -1
 StringUtils.getLevenshteinDistance("elephant", "hippo", 7) = 7
 StringUtils.getLevenshteinDistance("elephant", "hippo", 6) = -1
 StringUtils.getLevenshteinDistance("hippo", "elephant", 7) = 7
 StringUtils.getLevenshteinDistance("hippo", "elephant", 6) = -1
 

Parameters:

s - the first String, must not be null

t - the second String, must not be null

threshold - the target threshold, must not be negative

Returns:

result distance, or -1 if the distance would be greater than the threshold

Throws:

IllegalArgumentException - if either String input null or negative threshold