moa.tasks.CacheShuffledStream.java Source code

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Here is the source code for moa.tasks.CacheShuffledStream.java

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/*
 *    CacheShuffledStream.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.tasks;

import java.util.Random;

import weka.core.Instances;
import moa.core.ObjectRepository;
import moa.options.ClassOption;
import moa.options.IntOption;
import moa.streams.CachedInstancesStream;
import moa.streams.InstanceStream;

/**
 * Task for storing and shuffling examples in memory.
 *
 * @author Richard Kirkby (rkirkby@cs.waikato.ac.nz)
 * @version $Revision: 7 $
 */
public class CacheShuffledStream extends AbstractTask {

    @Override
    public String getPurposeString() {
        return "Stores and shuffles examples in memory.";
    }

    private static final long serialVersionUID = 1L;

    public ClassOption streamOption = new ClassOption("stream", 's', "Stream to cache and shuffle.",
            InstanceStream.class, "generators.RandomTreeGenerator");

    public IntOption maximumCacheSizeOption = new IntOption("maximumCacheSize", 'm',
            "Maximum number of instances to cache.", 1000000, 1, Integer.MAX_VALUE);

    public IntOption shuffleRandomSeedOption = new IntOption("shuffleRandomSeed", 'r',
            "Seed for random shuffling of instances.", 1);

    @Override
    protected Object doTaskImpl(TaskMonitor monitor, ObjectRepository repository) {
        InstanceStream stream = (InstanceStream) getPreparedClassOption(this.streamOption);
        Instances cache = new Instances(stream.getHeader(), 0);
        monitor.setCurrentActivity("Caching instances...", -1.0);
        while ((cache.numInstances() < this.maximumCacheSizeOption.getValue()) && stream.hasMoreInstances()) {
            cache.add(stream.nextInstance());
            if (cache.numInstances() % MainTask.INSTANCES_BETWEEN_MONITOR_UPDATES == 0) {
                if (monitor.taskShouldAbort()) {
                    return null;
                }
                long estimatedRemainingInstances = stream.estimatedRemainingInstances();
                long maxRemaining = this.maximumCacheSizeOption.getValue() - cache.numInstances();
                if ((estimatedRemainingInstances < 0) || (maxRemaining < estimatedRemainingInstances)) {
                    estimatedRemainingInstances = maxRemaining;
                }
                monitor.setCurrentActivityFractionComplete(estimatedRemainingInstances < 0 ? -1.0
                        : (double) cache.numInstances()
                                / (double) (cache.numInstances() + estimatedRemainingInstances));
            }
        }
        monitor.setCurrentActivity("Shuffling instances...", -1.0);
        cache.randomize(new Random(this.shuffleRandomSeedOption.getValue()));
        return new CachedInstancesStream(cache);
    }

    public Class<?> getTaskResultType() {
        return CachedInstancesStream.class;
    }
}