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https://issues.apache.org/jira/browse/MAHOUT-367?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Sean Owen resolved MAHOUT-367.
------------------------------
Resolution: Fixed
Fix Version/s: 0.4
Assignee: Sean Owen
Easy enough, I committed what I think is the right solution.
> IllegalArgumentException in AbstractJDBCModel when requesting
> mostSimilarItems for an item without preferences
> --------------------------------------------------------------------------------------------------------------
>
> Key: MAHOUT-367
> URL: https://issues.apache.org/jira/browse/MAHOUT-367
> Project: Mahout
> Issue Type: Bug
> Components: Collaborative Filtering
> Reporter: Sebastian Schelter
> Assignee: Sean Owen
> Fix For: 0.4
>
>
> I'm using GenericItemBasedRecommender together with MySQLJDBCDataModel for
> generating recommendations for an online shop. Whenever the recommender tries
> to calculate the most similar items for an item without preferences (e.g. a
> brand new product), an IllegalArgumentException is thrown as
> AbstractJDBCModel tries to create a GenericItemPreferenceArray from the empty
> preference list.
> Sample stacktrace:
> java.lang.IllegalArgumentException: size is less than 1
> at
> org.apache.mahout.cf.taste.impl.model.GenericItemPreferenceArray.<init>(GenericItemPreferenceArray.java:49)
> at
> org.apache.mahout.cf.taste.impl.model.GenericItemPreferenceArray.<init>(GenericItemPreferenceArray.java:56)
> at
> org.apache.mahout.cf.taste.impl.model.jdbc.AbstractJDBCDataModel.getPreferencesForItem(AbstractJDBCDataModel.java:441)
> at
> org.apache.mahout.cf.taste.impl.recommender.GenericItemBasedRecommender.doMostSimilarItems(GenericItemBasedRecommender.java:169)
> at
> org.apache.mahout.cf.taste.impl.recommender.GenericItemBasedRecommender.mostSimilarItems(GenericItemBasedRecommender.java:128)
> at
> org.apache.mahout.cf.taste.impl.recommender.GenericItemBasedRecommender.mostSimilarItems(GenericItemBasedRecommender.java:121)
> at
> de.zalando.recommendation.recommender.cf.TasteRecommenderAdapter.mostSimilarItems(TasteRecommenderAdapter.java:38)
> at
> de.zalando.recommendation.recommender.taste.cache.CachingRecommender.mostSimilarItems(CachingRecommender.java:39)
> at
> de.zalando.recommendation.recoreco.rest.RecommendationsRestController.mostSimilarItems(RecommendationsRestController.java:53)
> at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
> at
> sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
> at
> sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
> at java.lang.reflect.Method.invoke(Method.java:597)
> at
> org.springframework.web.bind.annotation.support.HandlerMethodInvoker.doInvokeMethod(HandlerMethodInvoker.java:710)
> at
> org.springframework.web.bind.annotation.support.HandlerMethodInvoker.invokeHandlerMethod(HandlerMethodInvoker.java:167)
> at
> org.springframework.web.servlet.mvc.annotation.AnnotationMethodHandlerAdapter.invokeHandlerMethod(AnnotationMethodHandlerAdapter.java:414)
> at
> org.springframework.web.servlet.mvc.annotation.AnnotationMethodHandlerAdapter.handle(AnnotationMethodHandlerAdapter.java:402)
> at
> org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:771)
> at
> org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:716)
> at
> org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:647)
> at
> org.springframework.web.servlet.FrameworkServlet.doGet(FrameworkServlet.java:552)
> at javax.servlet.http.HttpServlet.service(HttpServlet.java:617)
> at javax.servlet.http.HttpServlet.service(HttpServlet.java:717)
> at
> org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:290)
> at
> org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
> at
> org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:233)
> at
> org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:191)
> at
> org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:127)
> at
> org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:102)
> at
> org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:109)
> at
> org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:298)
> at
> org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:852)
> at
> org.apache.coyote.http11.Http11Protocol$Http11ConnectionHandler.process(Http11Protocol.java:588)
> at
> org.apache.tomcat.util.net.JIoEndpoint$Worker.run(JIoEndpoint.java:489)
> at java.lang.Thread.run(Thread.java:619)
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