expshell.DecisionTree.java Source code

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Here is the source code for expshell.DecisionTree.java

Source

/*
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package expshell;

import java.util.HashMap;
import java.util.Map;
import weka.classifiers.Classifier;
import weka.core.Instance;
import weka.core.Instances;
import static weka.core.Utils.log2;

/**
 *
 * @author YH Jonathan Kwok
 */
public class DecisionTree extends Classifier {
    private Instances data;

    @Override
    public void buildClassifier(Instances data) throws Exception {
        //this.data = data;
        double tempArray[] = { 1.0, 2.0, 1.0, 2.0, 3.0, 4.0 };
        System.out.println(calEntropy(tempArray));
        System.out.println(log2(10 / 3));
    }

    @Override
    public double classifyInstance(Instance i) {
        //I Know Nothing !!!!!!!!!!!!!!!!!!!!!!!!!!!
        return -1;
    }

    public Map<Double, Integer> makeMap(double arrayCount[]) {
        Map<Double, Integer> superMap = new HashMap<Double, Integer>();
        for (int i = 0; i < arrayCount.length; i++) {
            if (superMap.containsKey(arrayCount[i])) {
                superMap.replace(arrayCount[i], superMap.get(arrayCount[i]) + 1);
            } else {
                superMap.put(arrayCount[i], 1);
            }
        }
        return superMap;
    }

    public double calEntropy(double arrayCount[]) {
        double entropy;
        double whole = arrayCount.length;

        Map<Double, Integer> theMap = makeMap(arrayCount);

        //entropy = (arrayCounts[0]/whole)*log2(arrayCounts[0]/whole);
        entropy = 0;
        for (Double key : theMap.keySet()) {
            entropy -= (theMap.get(key) / whole) * log2(theMap.get(key) / whole);
        }

        return entropy;
    }

}