Example usage for weka.core Instances classAttribute

Introduction

In this page you can find the example usage for weka.core Instances classAttribute.

Prototype


publicAttribute classAttribute()

Source Link

Document

Returns the class attribute.

Usage

From source file:tubes1.myClassifiers.myID3.java

public TreeNode id3Node(Instances i) {
    TreeNode treeNode = new TreeNode();

    int[] count = calculateCount(i);
    for (int j = 0; j < count.length; j++) {
        int c = count[j];
        if (c == i.numInstances()) {
            treeNode.label = j;//w w w .ja v  a2  s  .co m
            return treeNode;
        }
    }

    if (i.numAttributes() <= 1) {
        int maxc = -1;
        int maxcj = -1;
        for (int j = 0; j < count.length; j++) {
            if (count[j] > maxc) {
                maxc = count[j];
                maxcj = j;
            }
        }
        treeNode.label = maxcj;
        return treeNode;
    }

    Attribute bestA = null;
    double bestAIG = -1;
    double entropyOfSet = entropy(i);
    for (int j = 0; j < i.numAttributes(); j++) {
        Attribute a = i.attribute(j);
        if (a != i.classAttribute()) {
            double aIG = infoGain(i, a, entropyOfSet);
            if (aIG > bestAIG) {
                bestAIG = aIG;
                bestA = a;
            }
        }
    }
    treeNode.decision = bestA;
    Instances[] subSets = splitData(i, bestA);
    for (Instances subSet : subSets) {
        if (subSet.numInstances() > 0) {
            double attributeValue = subSet.firstInstance().value(bestA);
            subSet.deleteAttributeAt(bestA.index());
            TreeNode newBranch = id3Node(subSet);
            newBranch.branchValue = attributeValue;
            treeNode.addBranch(newBranch);
        } else {
        }
    }
    return treeNode;
}

From source file:tubes1.myClassifiers.myID3.java

public double calculateAttributeProportion(Instances instances, Attribute attribute) {
    int numClasses = instances.classAttribute().numValues();

    return 0;//from  ww w .  j a v  a 2s .  c  o  m
}

From source file:tubes1.myClassifiers.myID3.java

public double infoGain(Instances instances, Attribute attribute, double entropyOfSet) {
    int numClasses = instances.classAttribute().numValues();
    int numInstances = instances.numInstances();
    HashMap<String, Integer> values = getAttributeValues(instances, attribute);
    double zigma = 0;
    Set<String> keys = values.keySet();
    for (int i = 0; i < keys.size(); i++) {
        String key = nthElement(keys, i);
        Instances instanceWithAttributeValue = filterInstanceWithAttributeValue(instances, attribute, key);
        zigma += (values.get(key) / numInstances) * entropy(instanceWithAttributeValue);
    }/*from w  w  w. j a va2 s. c o  m*/
    return entropyOfSet - zigma;
}