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

Class GenericBooleanPrefItemBasedRecommender

java.lang.Object

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

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

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

All Implemented Interfaces:

Refreshable, ItemBasedRecommender, Recommender

public final class GenericBooleanPrefItemBasedRecommender
extends GenericItemBasedRecommender

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

See Also:

GenericBooleanPrefUserBasedRecommender

Nested Class Summary

Nested classes/interfaces inherited from class org.apache.mahout.cf.taste.impl.recommender.GenericItemBasedRecommender

GenericItemBasedRecommender.MostSimilarEstimator

Constructor Summary

Constructors

Constructor and Description
GenericBooleanPrefItemBasedRecommender(DataModel dataModel, ItemSimilarity similarity)
GenericBooleanPrefItemBasedRecommender(DataModel dataModel, ItemSimilarity similarity, CandidateItemsStrategy candidateItemsStrategy, MostSimilarItemsCandidateItemsStrategy mostSimilarItemsCandidateItemsStrategy)

Method Summary

Modifier and Type	Method and Description
protected float	doEstimatePreference(long userID, PreferenceArray preferencesFromUser, 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.
String	toString()

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

estimatePreference, getDefaultMostSimilarItemsCandidateItemsStrategy, getSimilarity, mostSimilarItems, mostSimilarItems, mostSimilarItems, mostSimilarItems, mostSimilarItems, mostSimilarItems, recommend, recommendedBecause, 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

GenericBooleanPrefItemBasedRecommender

public GenericBooleanPrefItemBasedRecommender(DataModel dataModel,
                                              ItemSimilarity similarity)

GenericBooleanPrefItemBasedRecommender

public GenericBooleanPrefItemBasedRecommender(DataModel dataModel,
                                              ItemSimilarity similarity,
                                              CandidateItemsStrategy candidateItemsStrategy,
                                              MostSimilarItemsCandidateItemsStrategy mostSimilarItemsCandidateItemsStrategy)

Method Detail

doEstimatePreference

protected float doEstimatePreference(long userID,
                                     PreferenceArray preferencesFromUser,
                                     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.

Overrides:

doEstimatePreference in class GenericItemBasedRecommender

Throws:

TasteException

toString

public String toString()

Overrides:

toString in class GenericItemBasedRecommender