public void testDefaultUsedWhenTrainingDataSetHasNoExamples()
{
// tests RecursionBaseCase#1
DataSet ds = DataSetFactory.getRestaurantDataSet();
DecisionTreeLearner learner = new DecisionTreeLearner();
DataSet ds2 = ds.emptyDataSet();
Assert.AreEqual(0, ds2.size());
learner.Train(ds2);
Assert.AreEqual("Unable To Classify",
learner.Predict(ds.getExample(0)));
}
public void testClassificationReturnedWhenAllExamplesHaveTheSameClassification()
{
// tests RecursionBaseCase#2
DataSet ds = DataSetFactory.getRestaurantDataSet();
DecisionTreeLearner learner = new DecisionTreeLearner();
DataSet ds2 = ds.emptyDataSet();
// all 3 examples have the same classification (willWait = yes)
ds2.add(ds.getExample(0));
ds2.add(ds.getExample(2));
ds2.add(ds.getExample(3));
learner.Train(ds2);
Assert.AreEqual("Yes", learner.Predict(ds.getExample(0)));
}
public void testMajorityReturnedWhenAttributesToExamineIsEmpty()
{
// tests RecursionBaseCase#2
DataSet ds = DataSetFactory.getRestaurantDataSet();
DecisionTreeLearner learner = new DecisionTreeLearner();
DataSet ds2 = ds.emptyDataSet();
// 3 examples have classification = "yes" and one ,"no"
ds2.add(ds.getExample(0));
ds2.add(ds.getExample(1));// "no"
ds2.add(ds.getExample(2));
ds2.add(ds.getExample(3));
ds2.setSpecification(new MockDataSetSpecification("will_wait"));
learner.Train(ds2);
Assert.AreEqual("Yes", learner.Predict(ds.getExample(1)));
}