Class CosineSimilarity

java.lang.Object

org.apache.commons.text.similarity.CosineSimilarity

public class CosineSimilarity
extends Object

Measures the Cosine similarity of two vectors of an inner product space and compares the angle between them.

For further explanation about the Cosine Similarity, refer to https://en.wikipedia.org/wiki/Cosine_similarity.

Instances of this class are immutable and are safe for use by multiple concurrent threads.

Since:

1.0

Field Summary

Fields

Modifier and Type	Field	Description
(package private) static final CosineSimilarity	INSTANCE	The singleton instance.

Constructor Summary

Constructors

Constructor	Description
CosineSimilarity()	Construct a new instance.

Method Summary

Modifier and Type	Method	Description
Double	cosineSimilarity(Map<CharSequence, Integer> leftVector, Map<CharSequence, Integer> rightVector)	Calculates the cosine similarity for two given vectors.
private double	dot(Map<CharSequence, Integer> leftVector, Map<CharSequence, Integer> rightVector, Set<CharSequence> intersection)	Computes the dot product of two vectors.
private Set<CharSequence>	getIntersection(Map<CharSequence, Integer> leftVector, Map<CharSequence, Integer> rightVector)	Returns a set with keys common to the two given maps.

Methods inherited from class Object

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

Field Details

INSTANCE

static final CosineSimilarity INSTANCE

The singleton instance.

Constructor Details

CosineSimilarity

public CosineSimilarity()

Construct a new instance.

Method Details

cosineSimilarity

public Double cosineSimilarity(Map<CharSequence, Integer> leftVector,
 Map<CharSequence, Integer> rightVector)

Calculates the cosine similarity for two given vectors.

Parameters:

leftVector - left vector.

rightVector - right vector.

Returns:

cosine similarity between the two vectors.

dot

private double dot(Map<CharSequence, Integer> leftVector,
 Map<CharSequence, Integer> rightVector,
 Set<CharSequence> intersection)

Computes the dot product of two vectors. It ignores remaining elements. It means that if a vector is longer than other, then a smaller part of it will be used to compute the dot product.

Parameters:

leftVector - left vector.

rightVector - right vector.

intersection - common elements.

Returns:

The dot product.

getIntersection

private Set<CharSequence> getIntersection(Map<CharSequence, Integer> leftVector,
 Map<CharSequence, Integer> rightVector)

Returns a set with keys common to the two given maps.

Parameters:

leftVector - left vector map.

rightVector - right vector map.

Returns:

common strings.