moa.streams.filters.AddNoiseFilter.java Source code

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Here is the source code for moa.streams.filters.AddNoiseFilter.java

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/*
 *    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 3 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, see <http://www.gnu.org/licenses/>.
 *    
 */
package moa.streams.filters;

import java.util.Random;

import moa.core.AutoExpandVector;
import moa.core.DoubleVector;
import moa.core.GaussianEstimator;
import moa.core.InstancesHeader;
import moa.options.FloatOption;
import moa.options.IntOption;
import weka.core.Instance;

/**
 * Filter for adding random noise to examples in a stream.
 * Noise can be added to attribute values or to class labels.
 *
 * @author Richard Kirkby (rkirkby@cs.waikato.ac.nz)
 * @version $Revision: 7 $
 */
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>();
    }

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

    @Override
    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;
    }

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