Mahout（二） Similarity和 Recommender 的继承层次机构

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usersimilarity

相似度similarity分为usersimilarity和itemsimilarity的interface

interface 继承层次如下

itemsimilarityinterface的继承层次如下

userinterface的继承层次如下

其中的AbstractSimilarity

abstract class AbstractSimilarity extends AbstractItemSimilarity implements UserSimilarity

package org.apache.mahout.cf.taste.common;

public interface Refreshable {
      void refresh(Collection<Refreshable> alreadyRefreshed);
}

package org.apache.mahout.cf.taste.similarity;

public interface PreferenceInferrer extends Refreshable {
   float inferPreference(long userID, long itemID) throws TasteException;
}

public interface UserSimilarity extends Refreshable {
   double userSimilarity(long userID1, long userID2) throws TasteException;
   void setPreferenceInferrer(PreferenceInferrer inferrer);
}

public interface ItemSimilarity extends Refreshable{
     double itemSimilarity(long itemID1, long itemID2) throws TasteException;
     double[] itemSimilarities(long itemID1, long[] itemID2s) throws TasteException;
     long[] allSimilarItemIDs(long itemID) throws TasteException;
}

public abstract class AbstractItemSimilarity implements ItemSimilarity {
   @Override
     public long[] allSimilarItemIDs(long itemID) throws TasteException {}
   @Override
     public void refresh(Collection<Refreshable> alreadyRefreshed) {}
}

abstract class AbstractSimilarity extends AbstractItemSimilarity implements UserSimilarity {
      @Override
      public final void setPreferenceInferrer(PreferenceInferrer inferrer) {}
      @Override
      public double userSimilarity(long userID1, long userID2) throws TasteException {}
      @Override
      public final double itemSimilarity(long itemID1, long itemID2) throws TasteException {}
      @Override
      public double[] itemSimilarities(long itemID1, long[] itemID2s) throws TasteException {}
      @Override
      public final void refresh(Collection<Refreshable> alreadyRefreshed) {}
      @Override
      public final String toString() {}

      abstract double computeResult(int n, double sumXY, double sumX2, double sumY2, double sumXYdiff2);
}

Recommender interface继承层次如下

itemBasedRecommender和userbasedRecommender interface 继承自 Recommender 接口

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