com.planetj.taste.impl.recommender
Class CachingRecommender

java.lang.Object
  com.planetj.taste.impl.recommender.CachingRecommender

All Implemented Interfaces:

Refreshable, Recommender

public final class CachingRecommender
extends java.lang.Object
implements Recommender

A Recommender which caches the results from another Recommender in memory. Results are held by SoftReferences so that the JVM may reclaim memory from the recommendationCache in low-memory situations.

Author:

Sean Owen

Constructor Summary

CachingRecommender(Recommender recommender)

Method Summary

void	clear() Clears all cached recommendations.
void	clear(java.lang.Object userID) Clears cached recommendations for the given user.
double	estimatePreference(java.lang.Object userID, java.lang.Object itemID)
DataModel	getDataModel()
java.util.List<RecommendedItem>	recommend(java.lang.Object userID, int howMany)
java.util.List<RecommendedItem>	recommend(java.lang.Object userID, int howMany, Rescorer<Item> rescorer)
void	refresh() Triggers "refresh" -- whatever that means -- of the implementation.
void	removePreference(java.lang.Object userID, java.lang.Object itemID)
void	setPreference(java.lang.Object userID, java.lang.Object itemID, double value)
java.lang.String	toString()

Methods inherited from class java.lang.Object

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

Constructor Detail

CachingRecommender

public CachingRecommender(Recommender recommender)
                   throws TasteException

Throws:

TasteException

Method Detail

recommend

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

Specified by:

recommend in interface Recommender

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

@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

setPreference

public void setPreference(java.lang.Object userID,
                          java.lang.Object itemID,
                          double value)
                   throws TasteException

Specified by:

setPreference in interface Recommender

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

public void removePreference(java.lang.Object userID,
                             java.lang.Object itemID)
                      throws TasteException

Specified by:

removePreference in interface Recommender

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

@NotNull
public DataModel getDataModel()

Specified by:

getDataModel in interface Recommender

Returns:

DataModel used by this Recommender

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

clear

public void clear(java.lang.Object userID)

Clears cached recommendations for the given user.

Parameters:

userID - clear cached data associated with this user ID

clear

public void clear()

Clears all cached recommendations.

toString

@NotNull
public java.lang.String toString()

Overrides:

toString in class java.lang.Object