Example usage for weka.clusterers ClusterEvaluation mapClasses

Introduction

In this page you can find the example usage for weka.clusterers ClusterEvaluation mapClasses.

Prototype

public static void mapClasses(int numClusters, int lev, int[][] counts, int[] clusterTotals, double[] current,
        double[] best, int error) 

Source Link

Document

Finds the minimum error mapping of classes to clusters.

Usage

From source file:com.spread.experiment.tempuntilofficialrelease.ClassificationViaClustering108.java

License:Open Source License

/**
 * builds the classifier//from  w  w w.  j  a  v a 2  s  .  c  o m
 * 
 * @param data the training instances
 * @throws Exception if something goes wrong
 */
@Override
public void buildClassifier(Instances data) throws Exception {

    // can classifier handle the data?
    getCapabilities().testWithFail(data);

    // save original header (needed for clusters to classes output)
    m_OriginalHeader = data.stringFreeStructure();

    // remove class attribute for clusterer
    Instances clusterData = new Instances(data);
    clusterData.setClassIndex(-1);
    clusterData.deleteAttributeAt(data.classIndex());
    m_ClusteringHeader = clusterData.stringFreeStructure();

    if (m_ClusteringHeader.numAttributes() == 0) {
        System.err.println("Data contains only class attribute, defaulting to ZeroR model.");
        m_ZeroR = new ZeroR();
        m_ZeroR.buildClassifier(data);
    } else {
        m_ZeroR = null;

        // build clusterer
        m_ActualClusterer = AbstractClusterer.makeCopy(m_Clusterer);
        m_ActualClusterer.buildClusterer(clusterData);

        if (!getLabelAllClusters()) {

            // determine classes-to-clusters mapping
            ClusterEvaluation eval = new ClusterEvaluation();
            eval.setClusterer(m_ActualClusterer);
            eval.evaluateClusterer(clusterData);
            double[] clusterAssignments = eval.getClusterAssignments();
            int[][] counts = new int[eval.getNumClusters()][m_OriginalHeader.numClasses()];
            int[] clusterTotals = new int[eval.getNumClusters()];
            double[] best = new double[eval.getNumClusters() + 1];
            double[] current = new double[eval.getNumClusters() + 1];
            for (int i = 0; i < data.numInstances(); i++) {
                Instance instance = data.instance(i);
                if (!instance.classIsMissing()) {
                    counts[(int) clusterAssignments[i]][(int) instance.classValue()]++;
                    clusterTotals[(int) clusterAssignments[i]]++;
                }
            }
            best[eval.getNumClusters()] = Double.MAX_VALUE;
            ClusterEvaluation.mapClasses(eval.getNumClusters(), 0, counts, clusterTotals, current, best, 0);
            m_ClustersToClasses = new double[best.length];
            System.arraycopy(best, 0, m_ClustersToClasses, 0, best.length);
        } else {
            m_ClusterClassProbs = new double[m_ActualClusterer.numberOfClusters()][data.numClasses()];
            for (int i = 0; i < data.numInstances(); i++) {
                Instance clusterInstance = clusterData.instance(i);
                Instance originalInstance = data.instance(i);
                if (!originalInstance.classIsMissing()) {
                    double[] probs = m_ActualClusterer.distributionForInstance(clusterInstance);
                    for (int j = 0; j < probs.length; j++) {
                        m_ClusterClassProbs[j][(int) originalInstance.classValue()] += probs[j];
                    }
                }
            }
            for (int i = 0; i < m_ClusterClassProbs.length; i++) {
                Utils.normalize(m_ClusterClassProbs[i]);
            }
        }
    }
}

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