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java.lang.Objectorg.apache.mahout.cf.taste.impl.recommender.AbstractRecommender
org.apache.mahout.cf.taste.impl.recommender.ItemUserAverageRecommender
public final class ItemUserAverageRecommender
Like ItemAverageRecommender, except that estimated preferences are adjusted for the users' average
preference value. For example, say user X has not rated item Y. Item Y's average preference value is 3.5.
User X's average preference value is 4.2, and the average over all preference values is 4.0. User X prefers
items 0.2 higher on average, so, the estimated preference for user X, item Y is 3.5 + 0.2 = 3.7.
| Constructor Summary | |
|---|---|
ItemUserAverageRecommender(DataModel dataModel)
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| Method Summary | |
|---|---|
float |
estimatePreference(long userID,
long itemID)
|
List<RecommendedItem> |
recommend(long userID,
int howMany,
IDRescorer rescorer)
|
void |
refresh(Collection<Refreshable> alreadyRefreshed)
Triggers "refresh" -- whatever that means -- of the implementation. |
void |
removePreference(long userID,
long itemID)
Default implementation which just calls DataModel.removePreference(long, long) (Object, Object)}. |
void |
setPreference(long userID,
long itemID,
float value)
Default implementation which just calls DataModel.setPreference(long, long, float). |
String |
toString()
|
| Methods inherited from class org.apache.mahout.cf.taste.impl.recommender.AbstractRecommender |
|---|
getAllOtherItems, getDataModel, getDefaultCandidateItemsStrategy, recommend |
| Methods inherited from class java.lang.Object |
|---|
clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait |
| Constructor Detail |
|---|
public ItemUserAverageRecommender(DataModel dataModel)
throws TasteException
TasteException| Method Detail |
|---|
public List<RecommendedItem> recommend(long userID,
int howMany,
IDRescorer rescorer)
throws TasteException
userID - user for which recommendations are to be computedhowMany - desired number of recommendationsrescorer - rescoring function to apply before final list of recommendations is determined
List of recommended RecommendedItems, ordered from most strongly recommend to
least
TasteException - if an error occurs while accessing the DataModel
public float estimatePreference(long userID,
long itemID)
throws TasteException
userID - user ID whose preference is to be estimateditemID - item ID to estimate preference for
Double.NaN
TasteException - if an error occurs while accessing the DataModel
public void setPreference(long userID,
long itemID,
float value)
throws TasteException
AbstractRecommender
Default implementation which just calls DataModel.setPreference(long, long, float).
setPreference in interface RecommendersetPreference in class AbstractRecommenderuserID - user to set preference foritemID - item to set preference forvalue - preference value
TasteException - if an error occurs while accessing the DataModel
public void removePreference(long userID,
long itemID)
throws TasteException
AbstractRecommender
Default implementation which just calls DataModel.removePreference(long, long) (Object, Object)}.
removePreference in interface RecommenderremovePreference in class AbstractRecommenderuserID - user from which to remove preferenceitemID - item for which to remove preference
TasteException - if an error occurs while accessing the DataModelpublic void refresh(Collection<Refreshable> alreadyRefreshed)
Refreshable
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.
alreadyRefreshed - Refreshables that are known to have already been
refreshed as a result of an initial call to a Refreshable.refresh(Collection) method on some
object. This ensure that objects in a refresh dependency graph aren't refreshed twice
needlessly.public String toString()
toString in class Object
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