SEAGenerator.java

/*
 *    SEAGenerator.java
 *    Copyright (C) 2008 University of Waikato, Hamilton, New Zealand
 *    @author Albert Bifet
 *
 *    This program is free software; you can redistribute it and/or modify
 *    it under the terms of the GNU General Public License as published by
 *    the Free Software Foundation; either version 2 of the License, or
 *    (at your option) any later version.
 *
 *    This program is distributed in the hope that it will be useful,
 *    but WITHOUT ANY WARRANTY; without even the implied warranty of
 *    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *    GNU General Public License for more details.
 *
 *    You should have received a copy of the GNU General Public License
 *    along with this program; if not, write to the Free Software
 *    Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
 */
package tr.gov.ulakbim.jDenetX.streams.generators;

import tr.gov.ulakbim.jDenetX.core.InstancesHeader;
import tr.gov.ulakbim.jDenetX.core.ObjectRepository;
import tr.gov.ulakbim.jDenetX.options.AbstractOptionHandler;
import tr.gov.ulakbim.jDenetX.options.FlagOption;
import tr.gov.ulakbim.jDenetX.options.IntOption;
import tr.gov.ulakbim.jDenetX.streams.InstanceStream;
import tr.gov.ulakbim.jDenetX.tasks.TaskMonitor;
import weka.core.*;

import java.util.Random;

// Generator described in paper:
//  W. Nick Street and YongSeog Kim
//    "A streaming ensemble algorithm (SEA) for large-scale classification", 
//     KDD '01: Proceedings of the seventh ACM SIGKDD international conference on Knowledge discovery and data mining
//     377-382 2001.

// Notes:
// The built in functions are based on the paper 

public class SEAGenerator extends AbstractOptionHandler implements
        InstanceStream {

    @Override
    public String getPurposeString() {
        return "Generates SEA concepts functions.";
    }

    private static final long serialVersionUID = 1L;

    public IntOption functionOption = new IntOption("function", 'f',
            "Classification function used, as defined in the original paper.",
            1, 1, 4);

    public IntOption instanceRandomSeedOption = new IntOption(
            "instanceRandomSeed", 'i',
            "Seed for random generation of instances.", 1);

    public FlagOption balanceClassesOption = new FlagOption("balanceClasses",
            'b', "Balance the number of instances of each class.");

    public IntOption numInstancesConcept = new IntOption("numInstancesConcept", 'n',
            "The number of instances for each concept.", 0, 0, Integer.MAX_VALUE);

    public IntOption noisePercentageOption = new IntOption("noisePercentage",
            'n', "Percentage of noise to add to the data.", 10, 0, 100);

    protected interface ClassFunction {
        public int determineClass(double attrib1, double attrib2, double attrib3);
    }

    protected static ClassFunction[] classificationFunctions = {
            // function 1
            new ClassFunction() {
                public int determineClass(double attrib1, double attrib2, double attrib3) {
                    return (attrib1 + attrib2 <= 8) ? 0 : 1;
                }
            },
            // function 2
            new ClassFunction() {
                public int determineClass(double attrib1, double attrib2, double attrib3) {
                    return (attrib1 + attrib2 <= 9) ? 0 : 1;
                }
            },
            // function 3
            new ClassFunction() {
                public int determineClass(double attrib1, double attrib2, double attrib3) {
                    return (attrib1 + attrib2 <= 7) ? 0 : 1;
                }
            },
            // function 4
            new ClassFunction() {
                public int determineClass(double attrib1, double attrib2, double attrib3) {
                    return (attrib1 + attrib2 <= 9.5) ? 0 : 1;
                }
            }
    };

    protected InstancesHeader streamHeader;

    protected Random instanceRandom;

    protected boolean nextClassShouldBeZero;

    @Override
    protected void prepareForUseImpl(TaskMonitor monitor,
                                     ObjectRepository repository) {
        // generate header
        FastVector attributes = new FastVector();
        attributes.addElement(new Attribute("attrib1"));
        attributes.addElement(new Attribute("attrib2"));
        attributes.addElement(new Attribute("attrib3"));

        FastVector classLabels = new FastVector();
        classLabels.addElement("groupA");
        classLabels.addElement("groupB");
        attributes.addElement(new Attribute("class", classLabels));
        this.streamHeader = new InstancesHeader(new Instances(
                getCLICreationString(InstanceStream.class), attributes, 0));
        this.streamHeader.setClassIndex(this.streamHeader.numAttributes() - 1);
        restart();
    }

    public long estimatedRemainingInstances() {
        return -1;
    }

    public InstancesHeader getHeader() {
        return this.streamHeader;
    }

    public boolean hasMoreInstances() {
        return true;
    }

    public boolean isRestartable() {
        return true;
    }

    public Instance nextInstance() {
        double attrib1 = 0, attrib2 = 0, attrib3 = 0;
        int group = 0;
        boolean desiredClassFound = false;
        while (!desiredClassFound) {
            // generate attributes
            attrib1 = 10 * this.instanceRandom.nextDouble();
            attrib2 = 10 * this.instanceRandom.nextDouble();
            attrib3 = 10 * this.instanceRandom.nextDouble();

            // determine class
            group = classificationFunctions[this.functionOption.getValue() - 1]
                    .determineClass(attrib1, attrib2, attrib3);
            if (!this.balanceClassesOption.isSet()) {
                desiredClassFound = true;
            } else {
                // balance the classes
                if ((this.nextClassShouldBeZero && (group == 0))
                        || (!this.nextClassShouldBeZero && (group == 1))) {
                    desiredClassFound = true;
                    this.nextClassShouldBeZero = !this.nextClassShouldBeZero;
                } // else keep searching
            }
        }
        //Add Noise
        if ((1 + (this.instanceRandom.nextInt(100))) <= this.noisePercentageOption
                .getValue()) {
            group = (group == 0 ? 1 : 0);
        }

        // construct instance
        InstancesHeader header = getHeader();
        Instance inst = new DenseInstance(header.numAttributes());
        inst.setValue(0, attrib1);
        inst.setValue(1, attrib2);
        inst.setValue(2, attrib3);
        inst.setDataset(header);
        inst.setClassValue(group);
        return inst;
    }

    public void restart() {
        this.instanceRandom = new Random(this.instanceRandomSeedOption
                .getValue());
        this.nextClassShouldBeZero = false;
    }

    public void getDescription(StringBuilder sb, int indent) {
        // TODO Auto-generated method stub

    }

}