info.debatty.java.stringsimilarity

Class Jaccard

java.lang.Object

info.debatty.java.stringsimilarity.Jaccard

All Implemented Interfaces:

MetricStringDistance, NormalizedStringDistance, NormalizedStringSimilarity, StringDistance, StringSimilarity, Serializable

public class Jaccard
extends Object
implements MetricStringDistance, NormalizedStringDistance, NormalizedStringSimilarity

Each input string is converted into a set of n-grams, the Jaccard index is then computed as |V1 inter V2| / |V1 union V2|. Like Q-Gram distance, the input strings are first converted into sets of n-grams (sequences of n characters, also called k-shingles), but this time the cardinality of each n-gram is not taken into account. Distance is computed as 1 - cosine similarity. Jaccard index is a metric distance.

Author:

Thibault Debatty

See Also:

Serialized Form

Field Summary

Fields

Modifier and Type	Field and Description
protected int	k

Constructor Summary

Constructors

Constructor and Description
Jaccard()
Jaccard(int k) The strings are first transformed into sets of k-shingles (sequences of k characters), then Jaccard index is computed as |A inter B| / |A union B|.

Method Summary

Methods

Modifier and Type	Method and Description
double	distance(String s1, String s2)
int	getK() Return k, the length of k-shingles (aka n-grams)
double	similarity(String s1, String s2) Compute and return a measure of similarity between 2 strings.

Methods inherited from class java.lang.Object

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

Field Detail

k

protected final int k

Constructor Detail

Jaccard

public Jaccard(int k)

The strings are first transformed into sets of k-shingles (sequences of k characters), then Jaccard index is computed as |A inter B| / |A union B|. The default value of k is 3.

Parameters:

k -

Jaccard

public Jaccard()

Method Detail

similarity

public double similarity(String s1,
                String s2)

Description copied from interface: StringSimilarity

Compute and return a measure of similarity between 2 strings.

Specified by:

similarity in interface StringSimilarity

Returns:

similarity (0 means both strings are completely different)

distance

public double distance(String s1,
              String s2)

Specified by:

distance in interface MetricStringDistance

Specified by:

distance in interface StringDistance

getK

public int getK()

Return k, the length of k-shingles (aka n-grams)

Returns: