com.joliciel.jochre.stats.MeanAbsoluteDeviation.java Source code

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Here is the source code for com.joliciel.jochre.stats.MeanAbsoluteDeviation.java

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///////////////////////////////////////////////////////////////////////////////
//Copyright (C) 2012 Assaf Urieli
//
//This file is part of Jochre.
//
//Jochre is free software: you can redistribute it and/or modify
//it under the terms of the GNU Affero General Public License as published by
//the Free Software Foundation, either version 3 of the License, or
//(at your option) any later version.
//
//Jochre 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 Affero General Public License for more details.
//
//You should have received a copy of the GNU Affero General Public License
//along with Jochre.  If not, see <http://www.gnu.org/licenses/>.
//////////////////////////////////////////////////////////////////////////////
package com.joliciel.jochre.stats;

import java.util.ArrayList;
import java.util.List;

import org.apache.commons.math.stat.descriptive.moment.Mean;

/**
 * A mean absolute deviation to replace the standard deviation where outliers are a problem.
 * @author Assaf Urieli
 *
 */
public class MeanAbsoluteDeviation {
    List<Double> values = new ArrayList<Double>();
    double meanAbsoluteDeviation = Double.NaN;
    boolean dirty = false;

    public void clear() {
        values.clear();
        meanAbsoluteDeviation = Double.NaN;
        dirty = false;
    }

    public void increment(double value) {
        values.add(value);
        dirty = true;
    }

    public double getResult() {
        if (dirty) {
            Mean mean = new Mean();
            for (double value : values)
                mean.increment(value);
            double meanResult = mean.getResult();

            Mean deviationMean = new Mean();
            for (double value : values) {
                double deviation = value - meanResult;
                if (deviation < 0)
                    deviation = 0 - deviation;
                deviationMean.increment(deviation);
            }

            meanAbsoluteDeviation = deviationMean.getResult();

            dirty = false;
        }
        return meanAbsoluteDeviation;
    }
}