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java.lang.Objectorg.apache.mahout.cf.taste.impl.recommender.AbstractRecommender
org.apache.mahout.cf.taste.impl.recommender.svd.SVDRecommender
public final class SVDRecommender
A Recommender
that uses matrix factorization (a projection of users
and items onto a feature space)
Constructor Summary | |
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SVDRecommender(DataModel dataModel,
Factorizer factorizer)
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SVDRecommender(DataModel dataModel,
Factorizer factorizer,
CandidateItemsStrategy candidateItemsStrategy)
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SVDRecommender(DataModel dataModel,
Factorizer factorizer,
CandidateItemsStrategy candidateItemsStrategy,
PersistenceStrategy persistenceStrategy)
Create an SVDRecommender using a persistent store to cache factorizations. |
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SVDRecommender(DataModel dataModel,
Factorizer factorizer,
PersistenceStrategy persistenceStrategy)
Create an SVDRecommender using a persistent store to cache factorizations. |
Method Summary | |
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float |
estimatePreference(long userID,
long itemID)
a preference is estimated by computing the dot-product of the user and item feature vectors |
List<RecommendedItem> |
recommend(long userID,
int howMany,
IDRescorer rescorer)
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void |
refresh(Collection<Refreshable> alreadyRefreshed)
Refresh the data model and factorization. |
Methods inherited from class org.apache.mahout.cf.taste.impl.recommender.AbstractRecommender |
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getAllOtherItems, getDataModel, getDefaultCandidateItemsStrategy, recommend, removePreference, setPreference |
Methods inherited from class java.lang.Object |
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clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait |
Constructor Detail |
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public SVDRecommender(DataModel dataModel, Factorizer factorizer) throws TasteException
TasteException
public SVDRecommender(DataModel dataModel, Factorizer factorizer, CandidateItemsStrategy candidateItemsStrategy) throws TasteException
TasteException
public SVDRecommender(DataModel dataModel, Factorizer factorizer, PersistenceStrategy persistenceStrategy) throws TasteException
refresh
method recomputes the factorization and overwrites the store.
dataModel
- factorizer
- persistenceStrategy
-
TasteException
IOException
public SVDRecommender(DataModel dataModel, Factorizer factorizer, CandidateItemsStrategy candidateItemsStrategy, PersistenceStrategy persistenceStrategy) throws TasteException
refresh
method recomputes the factorization and overwrites the store.
dataModel
- factorizer
- candidateItemsStrategy
- persistenceStrategy
-
TasteException
Method Detail |
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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 RecommendedItem
s, 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 refresh(Collection<Refreshable> alreadyRefreshed)
alreadyRefreshed
- Refreshable
s 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.
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