Package opennlp.spellcheck.distance

Class LevenshteinDistance

java.lang.Object

opennlp.spellcheck.distance.LevenshteinDistance

All Implemented Interfaces:

EditDistance

public final class LevenshteinDistance
extends Object
implements EditDistance

Plain Levenshtein edit distance (insertions, deletions, substitutions; no transpositions). Offered as a selectable alternative to the default DamerauOSADistance, with which it shares the bounded EditDistance contract; the only behavioural difference is that an adjacent transposition costs two edits here (one deletion plus one insertion) rather than one.

The computation is bounded with early exit and is Unicode-aware: comparison happens on Unicode code points, so characters outside the Basic Multilingual Plane (e.g. many emoji) are treated as single symbols.

Instances are immutable and thread-safe.

Field Summary

Fields

Modifier and Type	Field	Description
static final LevenshteinDistance	INSTANCE	Shared, stateless instance.

Constructor Summary

Constructors

Constructor	Description
LevenshteinDistance()

Method Summary

Modifier and Type	Method	Description
int	distance(CharSequence a, CharSequence b, int max)	Computes the edit distance between a and b, giving up early once it is certain the distance exceeds max.

Methods inherited from class java.lang.Object

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

Field Details

INSTANCE

public static final LevenshteinDistance INSTANCE

Shared, stateless instance.

Constructor Details

LevenshteinDistance

public LevenshteinDistance()

Method Details

distance

public int distance(CharSequence a,
 CharSequence b,
 int max)

Description copied from interface: EditDistance

Computes the edit distance between a and b, giving up early once it is certain the distance exceeds max.

A max of 0 is permitted and meaningful: it asks only whether the two sequences are equal, returning 0 when they are and -1 as soon as any difference is found. It is the natural lower bound of the contract, not a degenerate case.

Specified by:

distance in interface EditDistance

Parameters:

a - the first sequence; must not be null

b - the second sequence; must not be null

max - the maximum acceptable distance; must not be negative (>= 0)

Returns:

the edit distance, or -1 if it is strictly greater than max