[SOLVED] RapidMiner says "The example set has no examples" and I don't know why

Cornelius

Hallo,

I invoke RapidMiner in my Java Application like this:

final Random random = new Random();
final Object[][] data = new Object[5][5];
for (int i = 0; i < 5; ++i) {
	for (int j = 0; j < 5; ++j) {
		if (j == 0) {
			data = "label" + random.nextInt();
		} else {
			data = random.nextInt();
		}
	}
}
final ExampleSet exampleSet = ExampleSetFactory.createExampleSet(data, 0);

RapidMiner.init();
final File process = new File("file.rmp");
final Process rapidMinerProcess = new Process(process);

final IOContainer ioContainer = rapidMinerProcess.run(new IOContainer(exampleSet));

But I get every time the following exception:

Exception in thread "main" com.rapidminer.operator.UserError: The example set has no examples
	at com.rapidminer.example.Tools.isNonEmpty(Tools.java:469)
	at com.rapidminer.operator.performance.PolynominalClassificationPerformanceEvaluator.checkCompatibility(PolynominalClassificationPerformanceEvaluator.java:105)
	at com.rapidminer.operator.performance.AbstractPerformanceEvaluator.doWork(AbstractPerformanceEvaluator.java:234)
	at com.rapidminer.operator.Operator.execute(Operator.java:834)
	at com.rapidminer.operator.execution.SimpleUnitExecutor.execute(SimpleUnitExecutor.java:51)
	at com.rapidminer.operator.ExecutionUnit.execute(ExecutionUnit.java:711)
	at com.rapidminer.operator.validation.ValidationChain.executeEvaluator(ValidationChain.java:223)
	at com.rapidminer.operator.validation.ValidationChain.evaluate(ValidationChain.java:324)
	at com.rapidminer.operator.validation.XValidation.performIteration(XValidation.java:162)
	at com.rapidminer.operator.validation.XValidation.estimatePerformance(XValidation.java:151)
	at com.rapidminer.operator.validation.ValidationChain.doWork(ValidationChain.java:273)
	at com.rapidminer.operator.Operator.execute(Operator.java:834)
	at com.rapidminer.operator.execution.SimpleUnitExecutor.execute(SimpleUnitExecutor.java:51)
	at com.rapidminer.operator.ExecutionUnit.execute(ExecutionUnit.java:711)
	at com.rapidminer.operator.OperatorChain.doWork(OperatorChain.java:379)
	at com.rapidminer.operator.Operator.execute(Operator.java:834)
	at com.rapidminer.Process.run(Process.java:925)
	at com.rapidminer.Process.run(Process.java:848)
	at com.rapidminer.Process.run(Process.java:807)
	at com.rapidminer.Process.run(Process.java:802)

My process is stored as XML and looks like this:

<?xml version="1.0" encoding="UTF-8" standalone="no"?>
<process version="5.2.008">
  <context>
    <input/>
    <output/>
    <macros/>
  </context>
  <operator activated="true" class="process" compatibility="5.2.008" expanded="true" name="Process">
    <process expanded="true" height="638" width="165">
      <operator activated="true" class="x_validation" compatibility="5.2.008" expanded="true" height="112" name="Validation" width="90" x="45" y="30">
        <process expanded="true" height="638" width="165">
          <operator activated="true" class="naive_bayes" compatibility="5.2.008" expanded="true" height="76" name="Naive Bayes" width="90" x="45" y="30"/>
          <connect from_port="training" to_op="Naive Bayes" to_port="training set"/>
          <connect from_op="Naive Bayes" from_port="model" to_port="model"/>
          <portSpacing port="source_training" spacing="0"/>
          <portSpacing port="sink_model" spacing="0"/>
          <portSpacing port="sink_through 1" spacing="0"/>
        </process>
        <process expanded="true" height="638" width="300">
          <operator activated="true" class="apply_model" compatibility="5.2.008" expanded="true" height="76" name="Apply Model" width="90" x="45" y="30">
            <list key="application_parameters"/>
          </operator>
          <operator activated="true" class="performance_classification" compatibility="5.2.008" expanded="true" height="76" name="Performance" width="90" x="180" y="30">
            <list key="class_weights"/>
          </operator>
          <connect from_port="model" to_op="Apply Model" to_port="model"/>
          <connect from_port="test set" to_op="Apply Model" to_port="unlabelled data"/>
          <connect from_op="Apply Model" from_port="labelled data" to_op="Performance" to_port="labelled data"/>
          <connect from_op="Performance" from_port="performance" to_port="averagable 1"/>
          <portSpacing port="source_model" spacing="0"/>
          <portSpacing port="source_test set" spacing="0"/>
          <portSpacing port="source_through 1" spacing="0"/>
          <portSpacing port="sink_averagable 1" spacing="0"/>
          <portSpacing port="sink_averagable 2" spacing="0"/>
        </process>
      </operator>
      <connect from_port="input 1" to_op="Validation" to_port="training"/>
      <connect from_op="Validation" from_port="averagable 1" to_port="result 1"/>
      <portSpacing port="source_input 1" spacing="0"/>
      <portSpacing port="source_input 2" spacing="0"/>
      <portSpacing port="sink_result 1" spacing="0"/>
      <portSpacing port="sink_result 2" spacing="0"/>
    </process>
  </operator>
</process>

Does anyone have an idea what's my mistake?

Thanks in advance.

Cornelius

MariusHelf

Hi Cornelius,

you are applying a 10-fold X-Validation on a dataset with 5 examples - that way of course some of the folds will be empty on the testing side. Just increase the number of examples, and your process will run fine.

Happy Coding!
~Marius

Cornelius

Oh! Of course. What a stupid mistake. Thanks a lot for your help.