org.lenskit.baseline

Class ItemMeanRatingItemScorer

java.lang.Object

org.lenskit.basic.AbstractItemScorer

org.lenskit.baseline.ItemMeanRatingItemScorer

All Implemented Interfaces:

java.io.Serializable, ItemScorer

@Shareable
public class ItemMeanRatingItemScorer
extends AbstractItemScorer
implements java.io.Serializable

Rating scorer that returns the item’s mean rating for all predictions.

If the item has no ratings, the global mean rating is returned.

This implements the baseline scorer (p_{u,i} = \mu + b_i), where (b_i) is the item’s average rating (less the global mean (\mu)).

See Also:

Serialized Form

Constructor Summary

Constructors

Constructor and Description
ItemMeanRatingItemScorer(RatingSummary summary, double damping) Construct a new scorer.

Method Summary

Modifier and Type	Method and Description
ResultMap	scoreWithDetails(long user, java.util.Collection<java.lang.Long> items) Score a collection of items and potentially return more details on the scores.
java.lang.String	toString()

Methods inherited from class org.lenskit.basic.AbstractItemScorer

score, score

Methods inherited from class java.lang.Object

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

Constructor Detail

ItemMeanRatingItemScorer

@Inject
public ItemMeanRatingItemScorer(RatingSummary summary,
                                        @MeanDamping
                                        double damping)

Construct a new scorer. This assumes ownership of the provided map.

Parameters:

summary - The rating summary.

damping - The damping factor.

Method Detail

scoreWithDetails

@Nonnull
public ResultMap scoreWithDetails(long user,
                                           @Nonnull
                                           java.util.Collection<java.lang.Long> items)

Description copied from interface: ItemScorer

Score a collection of items and potentially return more details on the scores.

Specified by:

scoreWithDetails in interface ItemScorer

Parameters:

user - The user ID for whom to generate scores.

items - The item to score.

Returns:

The scores for the items. This result set may not contain all requested items. Implementations that support additional details will return a subclass of ResultMap that provides access to those details.

toString

public java.lang.String toString()

Overrides:

toString in class java.lang.Object