edu.harvard.med.screensaver.analysis.ZScoreFunction.java Source code

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Here is the source code for edu.harvard.med.screensaver.analysis.ZScoreFunction.java

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// $HeadURL$
// $Id$
//
// Copyright  2006, 2010, 2011, 2012 by the President and Fellows of Harvard College.
// 
// Screensaver is an open-source project developed by the ICCB-L and NSRB labs
// at Harvard Medical School. This software is distributed under the terms of
// the GNU General Public License.

package edu.harvard.med.screensaver.analysis;

import java.util.Collection;

import org.apache.commons.math.stat.descriptive.moment.Mean;
import org.apache.commons.math.stat.descriptive.moment.StandardDeviation;
import org.apache.commons.math.util.ResizableDoubleArray;
import org.apache.log4j.Logger;

public class ZScoreFunction implements AggregateFunction<Double> {
    // static members

    private static Logger log = Logger.getLogger(ZScoreFunction.class);
    private boolean _initialized = false;
    private double _stdDev = Double.NaN;
    private double _mean = Double.NaN;

    public Double compute(Double valueController) {
        if (!_initialized) {
            throw new IllegalStateException("uninitialized");
        }
        return (valueController - _mean) / _stdDev;
    }

    public void initializeAggregates(Collection<Double> valuesToNormalizeOverController) {
        ResizableDoubleArray tmpDoubleValues = new ResizableDoubleArray();
        for (Double value : valuesToNormalizeOverController) {
            tmpDoubleValues.addElement(value);
        }
        _stdDev = new StandardDeviation().evaluate(tmpDoubleValues.getElements());
        _mean = new Mean().evaluate(tmpDoubleValues.getElements());
        _initialized = true;
    }

}