Google先决条件是非法参数异常 [英] Google preconditions illegal Argument exception

问题描述

我正在使用mahout为may应用程序创建一个基本推荐器。我的数据集没有任何偏好。这里是我的表如何看起来像

以下是设置mahout的方法

  MySQLJDBCDataModel jdbcModel2 = new MySQLJDBCDataModel（dataSource，user_viewed_song_statistics，
AUDIO_FK， USER_PROFILE_FK， AUDIO_FK， UVSS_DATE_CREATED）; 
 
 
 ItemSimilarity similarity = new LogLikelihoodSimilarity（jdbcModel2）; 
推荐推荐者= 
新增GenericBooleanPrefItemBasedRecommender（jdbcModel2，相似度）; 
 
（RecommendedItem item：recommender.recommend（1，1））
 System.out.println（item）; 
  

然而在运行这个之后。它返回了这个错误

 线程main中的异常java.lang.IllegalArgumentException 
在com.google.common中。 base.Preconditions.checkArgument（Preconditions.java:72）
 at org.apache.mahout.math.stats.LogLikelihood.logLikelihoodRatio（LogLikelihood.java:101）
 at org.apache.mahout.cf。 taste.impl.similarity.LogLikelihoodSimilarity.doItemSimilarity（LogLikelihoodSimilarity.java:102）
 at org.apache.mahout.cf.taste.impl.similarity.LogLikelihoodSimilarity.itemSimilarities（LogLikelihoodSimilarity.java:90）
 at org.apache.mahout.cf.taste.impl.recommender.GenericBooleanPrefItemBasedRecommender.doEstimatePreference（GenericBooleanPrefItemBasedRecommender.java:54）
 at org.apache.mahout.cf.taste.impl.recommender.GenericItemBasedRecommender $ Estimator.estimate（GenericItemBasedRecommender .java：312）
 at org.apache.mahout.cf.taste.impl.recommender.GenericItemBasedRecommender $ Estimator.estimate（GenericItemBasedRecommender.java:300） 
 at org.apache.mahout.cf.taste.impl.recommender.TopItems.getTopItems（TopItems.java:65）
 at org.apache.mahout.cf.taste.impl.recommender.GenericItemBasedRecommender。推荐（GenericItemBasedRecommender.java:131）
在org.apache.mahout.cf.taste.impl.recommender.AbstractRecommender.recommend（AbstractRecommender.java:63）
在Starter.main（Starter.java： 53）
  

解决方案

您正在使用非偏好项目推荐。与此问题类似

，我发现它很奇怪它会返回那种类型的异常。

  MySQLBooleanPrefJDBCDataModel jdbc = new MySQLBooleanPrefJDBCDataModel（dataSource，TABLE_NAME，USER_ID，ITEM_ID）; 
 CachingRecommender cachingRecommender =新的CachingRecommender（新的SlopeOneRecommender（jdbc））; 
 
 //获取用户3的5条建议
列表< RecommendedItem> items = cachingRecommender.recommend（3，5）; （推荐项目：项目）
 {
 System.out.println（item）; 
} 
  

希望这有助于您。

I am using mahout to create a basic recommender for may application. my data set does not have any preferences. here's how my table looks like

Here's how set up mahout

  MySQLJDBCDataModel jdbcModel2 = new MySQLJDBCDataModel(dataSource,"user_viewed_song_statistics",
                "AUDIO_FK","USER_PROFILE_FK","AUDIO_FK","UVSS_DATE_CREATED");


        ItemSimilarity similarity = new LogLikelihoodSimilarity(jdbcModel2);
        Recommender recommender = 
            new GenericBooleanPrefItemBasedRecommender(jdbcModel2, similarity);

       for(RecommendedItem item: recommender.recommend(1, 1))
           System.out.println(item);

However after running this. it returned this error

Exception in thread "main" java.lang.IllegalArgumentException
    at com.google.common.base.Preconditions.checkArgument(Preconditions.java:72)
    at org.apache.mahout.math.stats.LogLikelihood.logLikelihoodRatio(LogLikelihood.java:101)
    at org.apache.mahout.cf.taste.impl.similarity.LogLikelihoodSimilarity.doItemSimilarity(LogLikelihoodSimilarity.java:102)
    at org.apache.mahout.cf.taste.impl.similarity.LogLikelihoodSimilarity.itemSimilarities(LogLikelihoodSimilarity.java:90)
    at org.apache.mahout.cf.taste.impl.recommender.GenericBooleanPrefItemBasedRecommender.doEstimatePreference(GenericBooleanPrefItemBasedRecommender.java:54)
    at org.apache.mahout.cf.taste.impl.recommender.GenericItemBasedRecommender$Estimator.estimate(GenericItemBasedRecommender.java:312)
    at org.apache.mahout.cf.taste.impl.recommender.GenericItemBasedRecommender$Estimator.estimate(GenericItemBasedRecommender.java:300)
    at org.apache.mahout.cf.taste.impl.recommender.TopItems.getTopItems(TopItems.java:65)
    at org.apache.mahout.cf.taste.impl.recommender.GenericItemBasedRecommender.recommend(GenericItemBasedRecommender.java:131)
    at org.apache.mahout.cf.taste.impl.recommender.AbstractRecommender.recommend(AbstractRecommender.java:63)
    at Starter.main(Starter.java:53)

解决方案

You are using a Non-preference Item recommendation. Similar to this question

and I do find it weird that it is returning that type of an exception. what I've done is something like this.

MySQLBooleanPrefJDBCDataModel jdbc = new MySQLBooleanPrefJDBCDataModel(dataSource, TABLE_NAME, USER_ID, ITEM_ID);
CachingRecommender cachingRecommender = new CachingRecommender( new SlopeOneRecommender(jdbc));

// Get 5 recommendations for user 3
 List<RecommendedItem> items = cachingRecommender.recommend(3, 5);
  for (RecommendedItem item : items) {
        System.out.println(item);
  }

Hope this helps.

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