org.grouplens.lenskit.knn.user

Class UserUserItemScorer

java.lang.Object

org.grouplens.lenskit.basic.AbstractItemScorer

org.grouplens.lenskit.knn.user.UserUserItemScorer

All Implemented Interfaces:

ItemScorer

public class UserUserItemScorer
extends AbstractItemScorer

Field Summary

Fields

Modifier and Type	Field and Description
protected NeighborFinder	neighborFinder
static Symbol	NEIGHBORHOOD_SIZE_SYMBOL
static Symbol	NEIGHBORHOOD_WEIGHT_SYMBOL
protected UserVectorNormalizer	normalizer

Constructor Summary

Constructors

Constructor and Description
UserUserItemScorer(UserEventDAO dao, NeighborFinder nf, UserVectorNormalizer norm, int nnbrs, int minNbrs, Threshold thresh)

Method Summary

Modifier and Type	Method and Description
protected Long2ObjectMap<? extends Collection<Neighbor>>	findNeighbors(UserHistory<? extends Event> user, LongSet items) Find the neighbors for a user with respect to a collection of items.
protected Long2ObjectMap<SparseVector>	normalizeNeighborRatings(Collection<? extends Collection<Neighbor>> neighborhoods) Normalize all neighbor rating vectors, taking care to normalize each one only once.
void	score(long user, MutableSparseVector scores) Score items in a vector.

Methods inherited from class org.grouplens.lenskit.basic.AbstractItemScorer

score, score

Methods inherited from class java.lang.Object

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

Field Detail

NEIGHBORHOOD_SIZE_SYMBOL

public static final Symbol NEIGHBORHOOD_SIZE_SYMBOL

NEIGHBORHOOD_WEIGHT_SYMBOL

public static final Symbol NEIGHBORHOOD_WEIGHT_SYMBOL

neighborFinder

protected final NeighborFinder neighborFinder

normalizer

protected final UserVectorNormalizer normalizer

Constructor Detail

UserUserItemScorer

@Inject
public UserUserItemScorer(UserEventDAO dao,
                                  NeighborFinder nf,
                                  UserVectorNormalizer norm,
                                  @NeighborhoodSize
                                  int nnbrs,
                                  @MinNeighbors
                                  int minNbrs,
                                  @UserSimilarityThreshold
                                  Threshold thresh)

Method Detail

normalizeNeighborRatings

protected Long2ObjectMap<SparseVector> normalizeNeighborRatings(Collection<? extends Collection<Neighbor>> neighborhoods)

Normalize all neighbor rating vectors, taking care to normalize each one only once. FIXME: MDE does not like this method.

Parameters:

neighborhoods -

score

public void score(long user,
                  @Nonnull
                  MutableSparseVector scores)

Description copied from interface: ItemScorer

Score items in a vector. The key domain of the provided vector is the items to score, and the score method sets the values for each item to its score (or unsets it, if no score can be provided). The previous values are discarded.

Parameters:

user - The user ID.

scores - The score vector.

findNeighbors

protected Long2ObjectMap<? extends Collection<Neighbor>> findNeighbors(@Nonnull
                                                                       UserHistory<? extends Event> user,
                                                                       @Nonnull
                                                                       LongSet items)

Find the neighbors for a user with respect to a collection of items. For each item, the neighborhoodSize users closest to the provided user are returned.

Parameters:

user - The user's rating vector.

items - The items for which neighborhoods are requested.

Returns:

A mapping of item IDs to neighborhoods.