Mahout:采用斯皮尔曼相关系数基于相对排名定义相似度

//此处为UserSimilarity实现引入缓存的机制//采用斯皮尔曼相关系数基于相对排名定义相似度//其中加入了缓存的机制，将得到的结果进行内部的缓存//然后，当需要进行提供一个已经计算过的用户间相似度时，//就可以直接返回，而不需要进行重新的进行计算//但是这个方法的代价很高，很耗内存package byuser;import java.io.File;import java.io.IOException;import org.apache.mahout.cf.taste.common.TasteException;import org.apache.mahout.cf.taste.eval.RecommenderBuilder;import org.apache.mahout.cf.taste.eval.RecommenderEvaluator;import org.apache.mahout.cf.taste.impl.eval.AverageAbsoluteDifferenceRecommenderEvaluator;import org.apache.mahout.cf.taste.impl.neighborhood.NearestNUserNeighborhood;import org.apache.mahout.cf.taste.impl.recommender.GenericUserBasedRecommender;import org.apache.mahout.cf.taste.impl.similarity.CachingUserSimilarity;import org.apache.mahout.cf.taste.impl.similarity.SpearmanCorrelationSimilarity;import org.apache.mahout.cf.taste.model.DataModel;import org.apache.mahout.cf.taste.neighborhood.UserNeighborhood;import org.apache.mahout.cf.taste.recommender.Recommender;import org.apache.mahout.cf.taste.similarity.UserSimilarity;import org.apache.mahout.cf.taste.similarity.precompute.example.GroupLensDataModel;public class SpearManCorrelationSimilarityTest {public SpearManCorrelationSimilarityTest() throws TasteException, IOException{DataModel model = new GroupLensDataModel(new File("E:\\mahout项目\\examples\\ratings.dat"));RecommenderEvaluator evaluator = new AverageAbsoluteDifferenceRecommenderEvaluator();RecommenderBuilder recommenderBuilder = new RecommenderBuilder() {@Overridepublic Recommender buildRecommender(DataModel model) throws TasteException {UserSimilarity similarity = new CachingUserSimilarity(new SpearmanCorrelationSimilarity(model), model);UserNeighborhood neighborhood = new NearestNUserNeighborhood(100, similarity, model);return new GenericUserBasedRecommender(model, neighborhood, similarity);}};//这里evaluate()函数trainingPercentage从0.95升到0.99//从而让数据规模从5%减为1%double score = evaluator.evaluate(recommenderBuilder, null, model, 0.99, 0.05);System.out.println("采用斯皮尔曼相关系数的推荐引擎的评测得分是： " + score);}public static void main(String[] args) throws IOException, TasteException {// TODO Auto-generated method stubSpearManCorrelationSimilarityTest tt = new SpearManCorrelationSimilarityTest();}}

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