org.grouplens.lenskit.knn.item

Interface ItemSimilarity

All Known Implementing Classes:

ItemVectorSimilarity

@DefaultImplementation(value=ItemVectorSimilarity.class)
public interface ItemSimilarity

Compute the similarity between two items.

Since:

0.11

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 items.

Method Detail

similarity

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

Compute the similarity between two items.

Parameters:

i1 - The first item ID.

v1 - The first item vector.

i2 - The second item ID.

v2 - The second item vector.

Returns:

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

isSparse

boolean isSparse()

Query whether this similarity is sparse.

Returns:

true if the similarity function is sparse.

See Also:

VectorSimilarity.isSparse()

isSymmetric

boolean isSymmetric()

Query whether this similarity is symmetric.

Returns:

true if the similarity function is symmetric.

See Also:

VectorSimilarity.isSymmetric()