org.lenskit.basic

Class FallbackItemScorer

java.lang.Object

org.lenskit.basic.AbstractItemScorer

org.lenskit.basic.FallbackItemScorer

All Implemented Interfaces:

ItemScorer

public class FallbackItemScorer
extends AbstractItemScorer

Item scorer that combines a primary scorer with a baseline. This scorer is comprised of two other scorers, a primary scorer and a baseline scorer. It first scores items using the primary scorer, and then consults the baseline scorer for any items that the primary scorer could not score.

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static class	FallbackItemScorer.DynamicProvider An item scorer provider for opportunistically creating fallback scorers.

Constructor Summary

Constructors

Constructor and Description
FallbackItemScorer(ItemScorer primary, ItemScorer baseline)

Method Summary

Modifier and Type	Method and Description
ItemScorer	getBaselineScorer() Get the baseline scorer from this item scorer.
ItemScorer	getPrimaryScorer() Get the primary scorer from this item scorer.
FallbackResult	score(long user, long item) Score a single item.
ResultMap	scoreWithDetails(long user, java.util.Collection<java.lang.Long> items) Score a collection of items and potentially return more details on the scores.

Methods inherited from class org.lenskit.basic.AbstractItemScorer

score

Methods inherited from class java.lang.Object

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

Constructor Detail

FallbackItemScorer

@Inject
public FallbackItemScorer(@PrimaryScorer
                                  ItemScorer primary,
                                  @BaselineScorer
                                  ItemScorer baseline)

Method Detail

score

public FallbackResult score(long user,
                            long item)

Description copied from class: AbstractItemScorer

Score a single item.

This implementation delegates to ItemScorer.scoreWithDetails(long, Collection).

Specified by:

score in interface ItemScorer

Overrides:

score in class AbstractItemScorer

Parameters:

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

item - The item ID to score.

Returns:

The score, or null if no score can be generated.

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.

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.

getPrimaryScorer

@Nonnull
public ItemScorer getPrimaryScorer()

Get the primary scorer from this item scorer.

Returns:

The scorer’s primary scorer.

See Also:

PrimaryScorer

getBaselineScorer

@Nonnull
public ItemScorer getBaselineScorer()

Get the baseline scorer from this item scorer.

Returns:

The scorer’s baseline scorer.

See Also:

BaselineScorer