de.lmu.ifi.dbs.elki.distance.distancefunction.strings

Class NormalizedLevenshteinDistanceFunction

java.lang.Object

de.lmu.ifi.dbs.elki.distance.distancefunction.strings.NormalizedLevenshteinDistanceFunction

All Implemented Interfaces:

DistanceFunction<java.lang.String>, PrimitiveDistanceFunction<java.lang.String>

@Description(value="Levenshtein distance, normalized by average string length.")
 @Reference(authors="V. I. Levenshtein",
           title="Binary codes capable of correcting deletions, insertions and reversals",
           booktitle="Soviet physics doklady 10",
           bibkey="journals/misc/Levenshtein66")
public class NormalizedLevenshteinDistanceFunction
extends java.lang.Object
implements PrimitiveDistanceFunction<java.lang.String>

Levenshtein distance on strings, normalized by string length.

Note: this is no longer a metric, the triangle inequality is violated. Example: d("ab","bc")=1, d("ab", "abc")+d("abc","bc")=0.4+0.4=0.8

Reference:

V. I. Levenshtein
Binary codes capable of correcting deletions, insertions and reversals.
Soviet physics doklady. Vol. 10. 1966.

TODO: add case insensitive flag.

Since:

0.6.0

Author:

Felix Stahlberg, Erich Schubert

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static class	NormalizedLevenshteinDistanceFunction.Parameterizer Parameterization class.

Field Summary

Fields

Modifier and Type	Field and Description
static NormalizedLevenshteinDistanceFunction	STATIC_SENSITIVE Static instance, case sensitive.

Constructor Summary

Constructors

Constructor and Description
NormalizedLevenshteinDistanceFunction() Deprecated.

Method Summary

Modifier and Type	Method and Description
double	distance(java.lang.String o1, java.lang.String o2) Computes the distance between two given DatabaseObjects according to this distance function.
boolean	equals(java.lang.Object obj)
SimpleTypeInformation<? super java.lang.String>	getInputTypeRestriction() Get the input data type of the function.
int	hashCode()

Methods inherited from class java.lang.Object

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

Methods inherited from interface de.lmu.ifi.dbs.elki.distance.distancefunction.PrimitiveDistanceFunction

instantiate

Methods inherited from interface de.lmu.ifi.dbs.elki.distance.distancefunction.DistanceFunction

isMetric, isSquared, isSymmetric

Field Detail

STATIC_SENSITIVE

public static final NormalizedLevenshteinDistanceFunction STATIC_SENSITIVE

Static instance, case sensitive.

Constructor Detail

NormalizedLevenshteinDistanceFunction

@Deprecated
public NormalizedLevenshteinDistanceFunction()

Deprecated.

Constructor. Use static instance instead.

Method Detail

distance

public double distance(java.lang.String o1,
                       java.lang.String o2)

Description copied from interface: PrimitiveDistanceFunction

Computes the distance between two given DatabaseObjects according to this distance function.

Specified by:

distance in interface PrimitiveDistanceFunction<java.lang.String>

Parameters:

o1 - first DatabaseObject

o2 - second DatabaseObject

Returns:

the distance between two given DatabaseObjects according to this distance function

getInputTypeRestriction

public SimpleTypeInformation<? super java.lang.String> getInputTypeRestriction()

Description copied from interface: DistanceFunction

Get the input data type of the function.

Specified by:

getInputTypeRestriction in interface DistanceFunction<java.lang.String>

Specified by:

getInputTypeRestriction in interface PrimitiveDistanceFunction<java.lang.String>

Returns:

Type restriction

equals

public boolean equals(java.lang.Object obj)

Overrides:

equals in class java.lang.Object

hashCode

public int hashCode()

Overrides:

hashCode in class java.lang.Object