org.apache.mahout.cf.taste.impl.recommender

Class GenericBooleanPrefUserBasedRecommender

java.lang.Object

org.apache.mahout.cf.taste.impl.recommender.AbstractRecommender

org.apache.mahout.cf.taste.impl.recommender.GenericUserBasedRecommender

org.apache.mahout.cf.taste.impl.recommender.GenericBooleanPrefUserBasedRecommender

All Implemented Interfaces:

Refreshable, Recommender, UserBasedRecommender

public final class GenericBooleanPrefUserBasedRecommender
extends GenericUserBasedRecommender

A variant on GenericUserBasedRecommender which is appropriate for use when no notion of preference value exists in the data.

Constructor Summary

Constructors

Constructor and Description
GenericBooleanPrefUserBasedRecommender(DataModel dataModel, UserNeighborhood neighborhood, UserSimilarity similarity)

Method Summary

Modifier and Type	Method and Description
protected float	doEstimatePreference(long theUserID, long[] theNeighborhood, long itemID) This computation is in a technical sense, wrong, since in the domain of "boolean preference users" where all preference values are 1, this method should only ever return 1.0 or NaN.
protected FastIDSet	getAllOtherItems(long[] theNeighborhood, long theUserID, boolean includeKnownItems)
String	toString()

Methods inherited from class org.apache.mahout.cf.taste.impl.recommender.GenericUserBasedRecommender

estimatePreference, getSimilarity, mostSimilarUserIDs, mostSimilarUserIDs, recommend, refresh

Methods inherited from class org.apache.mahout.cf.taste.impl.recommender.AbstractRecommender

getAllOtherItems, getDataModel, getDefaultCandidateItemsStrategy, recommend, recommend, recommend, removePreference, setPreference

Methods inherited from class java.lang.Object

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

Methods inherited from interface org.apache.mahout.cf.taste.recommender.Recommender

getDataModel, recommend, recommend, recommend, removePreference, setPreference

Constructor Detail

GenericBooleanPrefUserBasedRecommender

public GenericBooleanPrefUserBasedRecommender(DataModel dataModel,
                                              UserNeighborhood neighborhood,
                                              UserSimilarity similarity)

Method Detail

doEstimatePreference

protected float doEstimatePreference(long theUserID,
                                     long[] theNeighborhood,
                                     long itemID)
                              throws TasteException

This computation is in a technical sense, wrong, since in the domain of "boolean preference users" where all preference values are 1, this method should only ever return 1.0 or NaN. This isn't terribly useful however since it means results can't be ranked by preference value (all are 1). So instead this returns a sum of similarities to any other user in the neighborhood who has also rated the item.

Overrides:

doEstimatePreference in class GenericUserBasedRecommender

Throws:

TasteException

getAllOtherItems

protected FastIDSet getAllOtherItems(long[] theNeighborhood,
                                     long theUserID,
                                     boolean includeKnownItems)
                              throws TasteException

Overrides:

getAllOtherItems in class GenericUserBasedRecommender

Throws:

TasteException

toString

public String toString()

Overrides:

toString in class GenericUserBasedRecommender