com.planetj.taste.impl.recommender
Class GenericUserBasedRecommender

java.lang.Object
  com.planetj.taste.impl.recommender.AbstractRecommender
      com.planetj.taste.impl.recommender.GenericUserBasedRecommender

All Implemented Interfaces:

Refreshable, Recommender, UserBasedRecommender

public final class GenericUserBasedRecommender
extends AbstractRecommender
implements UserBasedRecommender

A simple Recommender which uses a given DataModel and UserNeighborhood to produce recommendations.

Author:

Sean Owen

Constructor Summary

GenericUserBasedRecommender(DataModel dataModel, UserNeighborhood neighborhood, UserCorrelation correlation)

Method Summary

double	estimatePreference(java.lang.Object userID, java.lang.Object itemID)
java.util.List<User>	mostSimilarUsers(java.lang.Object userID, int howMany)
java.util.List<User>	mostSimilarUsers(java.lang.Object userID, int howMany, Rescorer<Pair<User,User>> rescorer)
java.util.List<RecommendedItem>	recommend(java.lang.Object userID, int howMany, Rescorer<Item> rescorer)
void	refresh() Triggers "refresh" -- whatever that means -- of the implementation. The general contract is that any Refreshable should always leave itself in a consistent, operational state, and that the refresh atomically updates internal state from old to new.
java.lang.String	toString()

Methods inherited from class com.planetj.taste.impl.recommender.AbstractRecommender

getAllOtherItems, getDataModel, recommend, removePreference, setPreference

Methods inherited from class java.lang.Object

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

Methods inherited from interface com.planetj.taste.recommender.Recommender

getDataModel, recommend, removePreference, setPreference

Constructor Detail

GenericUserBasedRecommender

public GenericUserBasedRecommender(DataModel dataModel,
                                   UserNeighborhood neighborhood,
                                   UserCorrelation correlation)

Method Detail

recommend

@NotNull
public java.util.List<RecommendedItem> recommend(java.lang.Object userID,
                                                         int howMany,
                                                         Rescorer<Item> rescorer)
                                          throws TasteException

Specified by:

recommend in interface Recommender

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

estimatePreference

public double estimatePreference(java.lang.Object userID,
                                 java.lang.Object itemID)
                          throws TasteException

Specified by:

estimatePreference in interface Recommender

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

mostSimilarUsers

@NotNull
public java.util.List<User> mostSimilarUsers(java.lang.Object userID,
                                                     int howMany)
                                      throws TasteException

Specified by:

mostSimilarUsers in interface UserBasedRecommender

Parameters:

userID - ID of User for which to find most similar other Users

howMany - desired number of most similar Users to find

Returns:

Users most similar to the given user

Throws:

TasteException - if an error occurs while accessing the DataModel

mostSimilarUsers

@NotNull
public java.util.List<User> mostSimilarUsers(java.lang.Object userID,
                                                     int howMany,
                                                     Rescorer<Pair<User,User>> rescorer)
                                      throws TasteException

Specified by:

mostSimilarUsers in interface UserBasedRecommender

Parameters:

userID - ID of User for which to find most similar other Users

howMany - desired number of most similar Users to find

rescorer - Rescorer which can adjust user-user correlation estimates used to determine most similar users

Returns:

Users most similar to the given user

Throws:

TasteException - if an error occurs while accessing the DataModel

refresh

public void refresh()

Triggers "refresh" -- whatever that means -- of the implementation. The general contract is that any Refreshable should always leave itself in a consistent, operational state, and that the refresh atomically updates internal state from old to new.

Specified by:

refresh in interface Refreshable

Overrides:

refresh in class AbstractRecommender

toString

@NotNull
public java.lang.String toString()

Overrides:

toString in class java.lang.Object