mlda.labelsDistribution.MinEntropy.java Source code

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Here is the source code for mlda.labelsDistribution.MinEntropy.java

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/*
 * This file is part of the MLDA.
 *
 * (c)  Jose Maria Moyano Murillo
 *      Eva Lucrecia Gibaja Galindo
 *      Sebastian Ventura Soto <sventura@uco.es>
 *
 * For the full copyright and license information, please view the LICENSE
 * file that was distributed with this source code.
 */

package mlda.labelsDistribution;

import mlda.base.MLDataMetric;
import mlda.util.Utils;
import mulan.data.MultiLabelInstances;
import weka.core.AttributeStats;
import weka.core.Instances;

/**
* Class implementing the Minimal entropy of labels
*
* @author Jose Maria Moyano Murillo
*/
public class MinEntropy extends MLDataMetric {

    /**
     * Constructor
     */
    public MinEntropy() {
        super("Minimal entropy of labels");
    }

    /**
     * Calculate metric value
     * 
     * @param mlData Multi-label dataset to which calculate the metric
     * @return Value of the metric
     */
    public double calculate(MultiLabelInstances mlData) {
        Instances instances = mlData.getDataSet();

        int nLabels = mlData.getNumLabels();
        int[] labels = mlData.getLabelIndices();

        double[] entropies = new double[nLabels];

        for (int i = 0; i < nLabels; i++) {
            AttributeStats attStats = instances.attributeStats(labels[i]);

            if (attStats.nominalCounts != null) {
                entropies[i] = Utils.entropy(attStats.nominalCounts);
            }
        }

        double minEntropy = Double.MAX_VALUE;
        for (double e : entropies) {
            if (e < minEntropy) {
                minEntropy = e;
            }
        }

        this.value = minEntropy;

        return value;
    }

}