org.grouplens.lenskit.vectors.similarity

Interface VectorSimilarity

All Known Implementing Classes:

CosineVectorSimilarity, DistanceVectorSimilarity, MutualInformationVectorSimilarity, PearsonCorrelation, SignificanceWeightedVectorSimilarity, SpearmanRankCorrelation

@DefaultImplementation(value=CosineVectorSimilarity.class)
public interface VectorSimilarity

Compute the similarity between sparse vectors.

Method Summary

Modifier and Type	Method and Description
boolean	isSparse() Query whether this similarity function is sparse (returns 0 for vectors with disjoint key sets).
boolean	isSymmetric() Query whether this similarity function is symmetric.
double	similarity(SparseVector vec1, SparseVector vec2) Compute the similarity between two vectors.

Method Detail

similarity

double similarity(SparseVector vec1,
                  SparseVector vec2)

Compute the similarity between two vectors.

Parameters:

vec1 - The left vector to compare.

vec2 - The right vector to compare.

Returns:

The similarity, in the range [-1,1].

isSparse

boolean isSparse()

Query whether this similarity function is sparse (returns 0 for vectors with disjoint key sets).

Returns:

true iff similarity(SparseVector, SparseVector) will always return true when applied to two vectors with no keys in common.

isSymmetric

boolean isSymmetric()

Query whether this similarity function is symmetric. Symmetric similarity functions return the same result when called on (A,B) and (B,A).

Returns:

true if the function is symmetric.