org.grouplens.lenskit

Interface ItemScorer

All Known Implementing Classes:

AbstractItemScorer, BiasedMFItemScorer, ConstantItemScorer, FallbackItemScorer, FunkSVDItemScorer, GlobalMeanRatingItemScorer, ItemItemScorer, ItemMeanRatingItemScorer, LeastSquaresItemScorer, PrecomputedItemScorer, RatingPredictorItemScorer, SimpleCachingItemScorer, SlopeOneItemScorer, UserMeanItemScorer, UserUserItemScorer, WeightedSlopeOneItemScorer

public interface ItemScorer

Score items for users. These scores can be predicted ratings, relevance scores, purchase probabilities, or any other real-valued score which can be assigned to an item for a particular user.

Since:

0.4

Compatibility

Public

Method Summary

Modifier and Type	Method and Description
SparseVector	score(long user, Collection<Long> items) Score a collection of items.
double	score(long user, long item) Score a single item.
void	score(long user, MutableSparseVector scores) Score items in a vector.

Method Detail

score

double score(long user,
             long item)

Score a single item.

Parameters:

user - The user ID for whom to generate a score.

item - The item ID to score.

Returns:

The score, or Double.NaN if no score can be generated.

score

@Nonnull
SparseVector score(long user,
                            @Nonnull
                            Collection<Long> items)

Score a collection of items.

Parameters:

user - The user ID for whom to generate scores.

items - The item to score.

Returns:

A mapping from item IDs to predicted preference. This mapping may not contain all requested items.

score

void score(long user,
           @Nonnull
           MutableSparseVector scores)

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.