org.grouplens.lenskit.knn.user

Class UserVectorSimilarity

java.lang.Object

org.grouplens.lenskit.knn.user.UserVectorSimilarity

All Implemented Interfaces:

Serializable, UserSimilarity

@Shareable
public class UserVectorSimilarity
extends Object
implements UserSimilarity, Serializable

Implementation of UserSimilarity that delegates to a vector similarity.

Since:

0.11

See Also:

Serialized Form

Constructor Summary

Constructors

Constructor and Description
UserVectorSimilarity(VectorSimilarity sim)

Method Summary

Modifier and Type	Method and Description
boolean	isSparse() Query whether this similarity is sparse.
boolean	isSymmetric() Query whether this similarity is symmetric.
double	similarity(long i1, SparseVector v1, long i2, SparseVector v2) Compute the similarity between two users.
String	toString()

Methods inherited from class java.lang.Object

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

Constructor Detail

UserVectorSimilarity

@Inject
public UserVectorSimilarity(VectorSimilarity sim)

Method Detail

similarity

public double similarity(long i1,
                         SparseVector v1,
                         long i2,
                         SparseVector v2)

Description copied from interface: UserSimilarity

Compute the similarity between two users.

Specified by:

similarity in interface UserSimilarity

Parameters:

i1 - The first user ID.

v1 - The first user vector.

i2 - The second user ID.

v2 - The second user vector.

Returns:

The similarity between the two users, in the range [0,1].

isSparse

public boolean isSparse()

Description copied from interface: UserSimilarity

Query whether this similarity is sparse.

Specified by:

isSparse in interface UserSimilarity

Returns:

true if the similarity function is sparse.

See Also:

VectorSimilarity.isSparse()

isSymmetric

public boolean isSymmetric()

Description copied from interface: UserSimilarity

Query whether this similarity is symmetric.

Warning: At present, asymmetric similarity functions may not produce correct results. In practice, this is not a problem, as most similarity functions are symmetric. Watch issue 151 for updates on this issue.

Specified by:

isSymmetric in interface UserSimilarity

Returns:

true if the similarity function is symmetric.

See Also:

VectorSimilarity.isSymmetric()

toString

public String toString()

Overrides:

toString in class Object