Package elki.distance.strings

Class NormalizedLevenshteinDistance

java.lang.Object

elki.distance.strings.NormalizedLevenshteinDistance

All Implemented Interfaces:

Distance<java.lang.String>, PrimitiveDistance<java.lang.String>

@Description("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 NormalizedLevenshteinDistance
extends java.lang.Object
implements PrimitiveDistance<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	Description
static class	NormalizedLevenshteinDistance.Par	Parameterization class.

Field Summary

Fields

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

Constructor Summary

Constructors

Constructor	Description
NormalizedLevenshteinDistance()	Deprecated.

Method Summary

Modifier and Type	Method	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 elki.distance.Distance

isMetric, isSquared, isSymmetric

Methods inherited from interface elki.distance.PrimitiveDistance

instantiate

Field Detail

STATIC_SENSITIVE

public static final NormalizedLevenshteinDistance STATIC_SENSITIVE

Static instance, case sensitive.

Constructor Detail

NormalizedLevenshteinDistance

@Deprecated
public NormalizedLevenshteinDistance()

Deprecated.

Constructor. Use static instance instead.

Method Detail

distance

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

Description copied from interface: PrimitiveDistance

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

Specified by:

distance in interface PrimitiveDistance<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: Distance

Get the input data type of the function.

Specified by:

getInputTypeRestriction in interface Distance<java.lang.String>

Specified by:

getInputTypeRestriction in interface PrimitiveDistance<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