info.debatty.java.stringsimilarity

Class Jaccard

java.lang.Object

info.debatty.java.stringsimilarity.ShingleBased

info.debatty.java.stringsimilarity.Jaccard

All Implemented Interfaces:

MetricStringDistance, NormalizedStringDistance, NormalizedStringSimilarity, StringDistance, StringSimilarity, Serializable

@Immutable
public class Jaccard
extends ShingleBased
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

Constructor Summary

Constructors

Constructor and Description
Jaccard() 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|.
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

Modifier and Type	Method and Description
double	distance(String s1, String s2) Distance is computed as 1 - similarity.
double	similarity(String s1, String s2) Compute Jaccard index: |A inter B| / |A union B|.

Methods inherited from class info.debatty.java.stringsimilarity.ShingleBased

getK, getProfile

Methods inherited from class java.lang.Object

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

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()

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.

Method Detail

similarity

public final double similarity(String s1,
                               String s2)

Compute Jaccard index: |A inter B| / |A union B|.

Specified by:

similarity in interface StringSimilarity

Parameters:

s1 - The first string to compare.

s2 - The second string to compare.

Returns:

The Jaccard index in the range [0, 1]

Throws:

NullPointerException - if s1 or s2 is null.

distance

public final double distance(String s1,
                             String s2)

Distance is computed as 1 - similarity.

Specified by:

distance in interface MetricStringDistance

Specified by:

distance in interface StringDistance

Parameters:

s1 - The first string to compare.

s2 - The second string to compare.

Returns:

1 - the Jaccard similarity.

Throws:

NullPointerException - if s1 or s2 is null.