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I am trying the

IoannisIoannis Member Posts: 4 Learner I
edited September 2020 in Help
I am trying the "Extract topics from Data (LDA)" operator and i get the error listed below. 
Data input = An excel file with one column with several cells as texts.
Read Excel > Process Documents from Data > Extract topics from Data (LDA)
text attribute: I put the name of the column as attribute "text".
I tried several number of topics and iterations but the warning message is the same.
I think that sth happens with the Attribute selection.
the "Process Documents from Data" produces wrong data types for the LDA.

Message says:
  • Exception: java.lang.NullPointerException
  • Message: null
  • Stack trace:
  • com.rapidminer.example.Example.getNominalValue(Example.java:97)
  • com.rapidminer.extension.operator.text_processing.modelling.mallet.MalletHelper.convertToInstanceList(MalletHelper.java:60)
  • com.rapidminer.extension.operator.text_processing.modelling.mallet.LDA_ExampleSet.getInstances(LDA_ExampleSet.java:69)
  • com.rapidminer.extension.operator.text_processing.modelling.mallet.LDA.doWork(LDA.java:125)
  • com.rapidminer.operator.Operator.execute(Operator.java:1022)
  • com.rapidminer.operator.execution.SimpleUnitExecutor.execute(SimpleUnitExecutor.java:77)
  • com.rapidminer.operator.ExecutionUnit$2.run(ExecutionUnit.java:812)
  • com.rapidminer.operator.ExecutionUnit$2.run(ExecutionUnit.java:807)
  • java.security.AccessController.doPrivileged(Native Method)
  • com.rapidminer.operator.ExecutionUnit.execute(ExecutionUnit.java:807)
  • com.rapidminer.operator.OperatorChain.doWork(OperatorChain.java:423)
  • com.rapidminer.operator.Operator.execute(Operator.java:1022)
  • com.rapidminer.Process.executeRoot(Process.java:1464)
  • com.rapidminer.Process.lambda$executeRootInPool$5(Process.java:1443)
  • com.rapidminer.studio.concurrency.internal.AbstractConcurrencyContext$AdaptedCallable.exec(AbstractConcurrencyContext.java:362)
  • java.util.concurrent.ForkJoinTask.doExec(ForkJoinTask.java:289)
  • java.util.concurrent.ForkJoinPool$WorkQueue.runTask(ForkJoinPool.java:1056)
  • java.util.concurrent.ForkJoinPool.runWorker(ForkJoinPool.java:1692)
  • java.util.concurrent.ForkJoinWorkerThread.run(ForkJoinWorkerThread.java:157)
Thank you in advance for your help!


  • IoannisIoannis Member Posts: 4 Learner I
    I think I found the solution. I would like to delete this Question @sgenzer  
    Thank you! 
  • mschmitzmschmitz Administrator, Moderator, Employee, RapidMiner Certified Analyst, RapidMiner Certified Expert, University Professor Posts: 3,128  RM Data Scientist
    this is a bug which should be 'fixed' this week. You will get a proper error message in the future.

    - Head of Data Science Services at RapidMiner -
    Dortmund, Germany
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