public static void decisionTreeDemo()
{
try
{
DataSet ds = DataSetFactory.getRestaurantDataSet();
DecisionTreeLearner learner = new DecisionTreeLearner();
learner.Train(ds);
System.Console.WriteLine("The Induced Decision Tree is ");
System.Console.WriteLine(learner.getDecisionTree());
int[] result = learner.Test(ds);
System.Console.WriteLine("\nThis Decision Tree classifies the data set with "
+ result[0]
+ " successes"
+ " and "
+ result[1]
+ " failures");
System.Console.WriteLine("\n");
}
catch (Exception e)
{
System.Console.WriteLine("Decision Tree Demo Failed ");
throw e;
}
}
public void testInducedTreeClassifiesDataSetCorrectly()
{
DataSet ds = DataSetFactory.getRestaurantDataSet();
DecisionTreeLearner learner = new DecisionTreeLearner();
learner.Train(ds);
int[] result = learner.Test(ds);
Assert.AreEqual(12, result[0]);
Assert.AreEqual(0, result[1]);
}
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)));
}