AddNoiseFilter.java

/*
 *    AddNoiseFilter.java
 *    Copyright (C) 2007 University of Waikato, Hamilton, New Zealand
 *    @author Richard Kirkby (rkirkby@cs.waikato.ac.nz)
 *
 *    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.filters;

import tr.gov.ulakbim.jDenetX.core.AutoExpandVector;
import tr.gov.ulakbim.jDenetX.core.DoubleVector;
import tr.gov.ulakbim.jDenetX.core.GaussianEstimator;
import tr.gov.ulakbim.jDenetX.core.InstancesHeader;
import tr.gov.ulakbim.jDenetX.options.FloatOption;
import tr.gov.ulakbim.jDenetX.options.IntOption;
import weka.core.Instance;

import java.util.Random;

public class AddNoiseFilter extends AbstractStreamFilter {

    @Override
    public String getPurposeString() {
        return "Adds random noise to examples in a stream.";
    }

    private static final long serialVersionUID = 1L;

    public IntOption randomSeedOption = new IntOption("randomSeed", 'r',
            "Seed for random noise.", 1);

    public FloatOption attNoiseFractionOption = new FloatOption("attNoise",
            'a', "The fraction of attribute values to disturb.", 0.1, 0.0, 1.0);

    public FloatOption classNoiseFractionOption = new FloatOption("classNoise",
            'c', "The fraction of class labels to disturb.", 0.1, 0.0, 1.0);

    protected Random random;

    protected AutoExpandVector<Object> attValObservers;

    @Override
    protected void restartImpl() {
        this.random = new Random(this.randomSeedOption.getValue());
        this.attValObservers = new AutoExpandVector<Object>();
    }

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

    public Instance nextInstance() {
        Instance inst = (Instance) this.inputStream.nextInstance().copy();
        for (int i = 0; i < inst.numAttributes(); i++) {
            double noiseFrac = i == inst.classIndex() ? this.classNoiseFractionOption
                    .getValue()
                    : this.attNoiseFractionOption.getValue();
            if (inst.attribute(i).isNominal()) {
                DoubleVector obs = (DoubleVector) this.attValObservers.get(i);
                if (obs == null) {
                    obs = new DoubleVector();
                    this.attValObservers.set(i, obs);
                }
                int originalVal = (int) inst.value(i);
                if (!inst.isMissing(i)) {
                    obs.addToValue(originalVal, inst.weight());
                }
                if ((this.random.nextDouble() < noiseFrac)
                        && (obs.numNonZeroEntries() > 1)) {
                    do {
                        inst.setValue(i, this.random.nextInt(obs.numValues()));
                    } while (((int) inst.value(i) == originalVal)
                            || (obs.getValue((int) inst.value(i)) == 0.0));
                }
            } else {
                GaussianEstimator obs = (GaussianEstimator) this.attValObservers
                        .get(i);
                if (obs == null) {
                    obs = new GaussianEstimator();
                    this.attValObservers.set(i, obs);
                }
                obs.addObservation(inst.value(i), inst.weight());
                inst.setValue(i, inst.value(i) + this.random.nextGaussian()
                        * obs.getStdDev() * noiseFrac);
            }
        }
        return inst;
    }

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