org.apache.mahout.cf.taste.recommender

Interface Recommender

All Superinterfaces:

Refreshable

All Known Subinterfaces:

ItemBasedRecommender, UserBasedRecommender

All Known Implementing Classes:

AbstractRecommender, CachingRecommender, GenericBooleanPrefItemBasedRecommender, GenericBooleanPrefUserBasedRecommender, GenericItemBasedRecommender, GenericUserBasedRecommender, ItemAverageRecommender, ItemUserAverageRecommender, RandomRecommender, SVDRecommender

public interface Recommender
extends Refreshable

Implementations of this interface can recommend items for a user. Implementations will likely take advantage of several classes in other packages here to compute this.

Method Summary

Modifier and Type	Method and Description
float	estimatePreference(long userID, long itemID)
DataModel	getDataModel()
List<RecommendedItem>	recommend(long userID, int howMany)
List<RecommendedItem>	recommend(long userID, int howMany, boolean includeKnownItems)
List<RecommendedItem>	recommend(long userID, int howMany, IDRescorer rescorer)
List<RecommendedItem>	recommend(long userID, int howMany, IDRescorer rescorer, boolean includeKnownItems)
void	removePreference(long userID, long itemID)
void	setPreference(long userID, long itemID, float value)

Methods inherited from interface org.apache.mahout.cf.taste.common.Refreshable

refresh

Method Detail

recommend

List<RecommendedItem> recommend(long userID,
                                int howMany)
                         throws TasteException

Parameters:

userID - user for which recommendations are to be computed

howMany - desired number of recommendations

Returns:

List of recommended RecommendedItems, ordered from most strongly recommend to least

Throws:

TasteException - if an error occurs while accessing the DataModel

recommend

List<RecommendedItem> recommend(long userID,
                                int howMany,
                                boolean includeKnownItems)
                         throws TasteException

Parameters:

userID - user for which recommendations are to be computed

howMany - desired number of recommendations

includeKnownItems - whether to include items already known by the user in recommendations

Returns:

List of recommended RecommendedItems, ordered from most strongly recommend to least

Throws:

TasteException - if an error occurs while accessing the DataModel

recommend

List<RecommendedItem> recommend(long userID,
                                int howMany,
                                IDRescorer rescorer)
                         throws TasteException

Parameters:

userID - user for which recommendations are to be computed

howMany - desired number of recommendations

rescorer - rescoring function to apply before final list of recommendations is determined

Returns:

List of recommended RecommendedItems, ordered from most strongly recommend to least

Throws:

TasteException - if an error occurs while accessing the DataModel

recommend

List<RecommendedItem> recommend(long userID,
                                int howMany,
                                IDRescorer rescorer,
                                boolean includeKnownItems)
                         throws TasteException

Parameters:

userID - user for which recommendations are to be computed

howMany - desired number of recommendations

rescorer - rescoring function to apply before final list of recommendations is determined

includeKnownItems - whether to include items already known by the user in recommendations

Returns:

List of recommended RecommendedItems, ordered from most strongly recommend to least

Throws:

TasteException - if an error occurs while accessing the DataModel

estimatePreference

float estimatePreference(long userID,
                         long itemID)
                  throws TasteException

Parameters:

userID - user ID whose preference is to be estimated

itemID - item ID to estimate preference for

Returns:

an estimated preference if the user has not expressed a preference for the item, or else the user's actual preference for the item. If a preference cannot be estimated, returns Double.NaN

Throws:

TasteException - if an error occurs while accessing the DataModel

setPreference

void setPreference(long userID,
                   long itemID,
                   float value)
            throws TasteException

Parameters:

userID - user to set preference for

itemID - item to set preference for

value - preference value

Throws:

TasteException - if an error occurs while accessing the DataModel

removePreference

void removePreference(long userID,
                      long itemID)
               throws TasteException

Parameters:

userID - user from which to remove preference

itemID - item for which to remove preference

Throws:

TasteException - if an error occurs while accessing the DataModel

getDataModel

DataModel getDataModel()

Returns:

underlying DataModel used by this Recommender implementation