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jfreechart example source code file (MovingAverage.java)

This example jfreechart source code file (MovingAverage.java) is included in the DevDaily.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" TM.

Java - jfreechart tags/keywords

illegalargumentexception, illegalargumentexception, null, null, number, regulartimeperiod, string, string, timeseries, timeseries, timeseriescollection, timeseriesdataitem, xydataset, xyseries

The jfreechart MovingAverage.java source code

/* ===========================================================
 * JFreeChart : a free chart library for the Java(tm) platform
 * ===========================================================
 *
 * (C) Copyright 2000-2009, by Object Refinery Limited and Contributors.
 *
 * Project Info:  http://www.jfree.org/jfreechart/index.html
 *
 * This library is free software; you can redistribute it and/or modify it
 * under the terms of the GNU Lesser General Public License as published by
 * the Free Software Foundation; either version 2.1 of the License, or
 * (at your option) any later version.
 *
 * This library 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 Lesser General Public
 * License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with this library; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301,
 * USA.
 *
 * [Java is a trademark or registered trademark of Sun Microsystems, Inc.
 * in the United States and other countries.]
 *
 * ------------------
 * MovingAverage.java
 * ------------------
 * (C) Copyright 2003-2009, by Object Refinery Limited.
 *
 * Original Author:  David Gilbert (for Object Refinery Limited);
 * Contributor(s):   Benoit Xhenseval;
 *
 * Changes
 * -------
 * 28-Jan-2003 : Version 1 (DG);
 * 10-Mar-2003 : Added createPointMovingAverage() method contributed by Benoit
 *               Xhenseval (DG);
 * 01-Aug-2003 : Added new method for TimeSeriesCollection, and fixed bug in
 *               XYDataset method (DG);
 * 15-Jul-2004 : Switched getX() with getXValue() and getY() with
 *               getYValue() (DG);
 * 11-Jan-2005 : Removed deprecated code in preparation for the 1.0.0
 *               release (DG);
 *
 */

package org.jfree.data.time;

import org.jfree.data.xy.XYDataset;
import org.jfree.data.xy.XYSeries;
import org.jfree.data.xy.XYSeriesCollection;

/**
 * A utility class for calculating moving averages of time series data.
 */
public class MovingAverage {

    /**
     * Creates a new {@link TimeSeriesCollection} containing a moving average
     * series for each series in the source collection.
     *
     * @param source  the source collection.
     * @param suffix  the suffix added to each source series name to create the
     *                corresponding moving average series name.
     * @param periodCount  the number of periods in the moving average
     *                     calculation.
     * @param skip  the number of initial periods to skip.
     *
     * @return A collection of moving average time series.
     */
    public static TimeSeriesCollection createMovingAverage(
            TimeSeriesCollection source, String suffix, int periodCount,
            int skip) {

        if (source == null) {
            throw new IllegalArgumentException("Null 'source' argument.");
        }
        if (periodCount < 1) {
            throw new IllegalArgumentException("periodCount must be greater "
                    + "than or equal to 1.");
        }

        TimeSeriesCollection result = new TimeSeriesCollection();
        for (int i = 0; i < source.getSeriesCount(); i++) {
            TimeSeries sourceSeries = source.getSeries(i);
            TimeSeries maSeries = createMovingAverage(sourceSeries,
                    sourceSeries.getKey() + suffix, periodCount, skip);
            result.addSeries(maSeries);
        }
        return result;

    }

    /**
     * Creates a new {@link TimeSeries} containing moving average values for
     * the given series.  If the series is empty (contains zero items), the
     * result is an empty series.
     *
     * @param source  the source series.
     * @param name  the name of the new series.
     * @param periodCount  the number of periods used in the average
     *                     calculation.
     * @param skip  the number of initial periods to skip.
     *
     * @return The moving average series.
     */
    public static TimeSeries createMovingAverage(TimeSeries source,
            String name, int periodCount, int skip) {

        if (source == null) {
            throw new IllegalArgumentException("Null source.");
        }
        if (periodCount < 1) {
            throw new IllegalArgumentException("periodCount must be greater " +
                    "than or equal to 1.");

        }

        TimeSeries result = new TimeSeries(name);

        if (source.getItemCount() > 0) {

            // if the initial averaging period is to be excluded, then
            // calculate the index of the
            // first data item to have an average calculated...
            long firstSerial
                    = source.getDataItem(0).getPeriod().getSerialIndex() + skip;

            for (int i = source.getItemCount() - 1; i >= 0; i--) {

                // get the current data item...
                TimeSeriesDataItem current = source.getDataItem(i);
                RegularTimePeriod period = current.getPeriod();
                long serial = period.getSerialIndex();

                if (serial >= firstSerial) {
                    // work out the average for the earlier values...
                    int n = 0;
                    double sum = 0.0;
                    long serialLimit = period.getSerialIndex() - periodCount;
                    int offset = 0;
                    boolean finished = false;

                    while ((offset < periodCount) && (!finished)) {
                        if ((i - offset) >= 0) {
                            TimeSeriesDataItem item = source.getDataItem(
                                    i - offset);
                            RegularTimePeriod p = item.getPeriod();
                            Number v = item.getValue();
                            long currentIndex = p.getSerialIndex();
                            if (currentIndex > serialLimit) {
                                if (v != null) {
                                    sum = sum + v.doubleValue();
                                    n = n + 1;
                                }
                            }
                            else {
                                finished = true;
                            }
                        }
                        offset = offset + 1;
                    }
                    if (n > 0) {
                        result.add(period, sum / n);
                    }
                    else {
                        result.add(period, null);
                    }
                }

            }
        }

        return result;

    }

    /**
     * Creates a new {@link TimeSeries} containing moving average values for
     * the given series, calculated by number of points (irrespective of the
     * 'age' of those points).  If the series is empty (contains zero items),
     * the result is an empty series.
     * <p>
     * Developed by Benoit Xhenseval (www.ObjectLab.co.uk).
     *
     * @param source  the source series.
     * @param name  the name of the new series.
     * @param pointCount  the number of POINTS used in the average calculation
     *                    (not periods!)
     *
     * @return The moving average series.
     */
    public static TimeSeries createPointMovingAverage(TimeSeries source,
            String name, int pointCount) {

        if (source == null) {
            throw new IllegalArgumentException("Null 'source'.");
        }
        if (pointCount < 2) {
            throw new IllegalArgumentException("periodCount must be greater " +
                    "than or equal to 2.");
        }

        TimeSeries result = new TimeSeries(name);
        double rollingSumForPeriod = 0.0;
        for (int i = 0; i < source.getItemCount(); i++) {
            // get the current data item...
            TimeSeriesDataItem current = source.getDataItem(i);
            RegularTimePeriod period = current.getPeriod();
            rollingSumForPeriod += current.getValue().doubleValue();

            if (i > pointCount - 1) {
                // remove the point i-periodCount out of the rolling sum.
                TimeSeriesDataItem startOfMovingAvg = source.getDataItem(
                        i - pointCount);
                rollingSumForPeriod -= startOfMovingAvg.getValue()
                        .doubleValue();
                result.add(period, rollingSumForPeriod / pointCount);
            }
            else if (i == pointCount - 1) {
                result.add(period, rollingSumForPeriod / pointCount);
            }
        }
        return result;
    }

    /**
     * Creates a new {@link XYDataset} containing the moving averages of each
     * series in the <code>source dataset.
     *
     * @param source  the source dataset.
     * @param suffix  the string to append to source series names to create
     *                target series names.
     * @param period  the averaging period.
     * @param skip  the length of the initial skip period.
     *
     * @return The dataset.
     */
    public static XYDataset createMovingAverage(XYDataset source, String suffix,
            long period, long skip) {

        return createMovingAverage(source, suffix, (double) period,
                (double) skip);

    }


    /**
     * Creates a new {@link XYDataset} containing the moving averages of each
     * series in the <code>source dataset.
     *
     * @param source  the source dataset.
     * @param suffix  the string to append to source series names to create
     *                target series names.
     * @param period  the averaging period.
     * @param skip  the length of the initial skip period.
     *
     * @return The dataset.
     */
    public static XYDataset createMovingAverage(XYDataset source,
            String suffix, double period, double skip) {

        if (source == null) {
            throw new IllegalArgumentException("Null source (XYDataset).");
        }

        XYSeriesCollection result = new XYSeriesCollection();

        for (int i = 0; i < source.getSeriesCount(); i++) {
            XYSeries s = createMovingAverage(source, i, source.getSeriesKey(i)
                    + suffix, period, skip);
            result.addSeries(s);
        }

        return result;

    }

    /**
     * Creates a new {@link XYSeries} containing the moving averages of one
     * series in the <code>source dataset.
     *
     * @param source  the source dataset.
     * @param series  the series index (zero based).
     * @param name  the name for the new series.
     * @param period  the averaging period.
     * @param skip  the length of the initial skip period.
     *
     * @return The dataset.
     */
    public static XYSeries createMovingAverage(XYDataset source,
            int series, String name, double period, double skip) {

        if (source == null) {
            throw new IllegalArgumentException("Null source (XYDataset).");
        }
        if (period < Double.MIN_VALUE) {
            throw new IllegalArgumentException("period must be positive.");
        }
        if (skip < 0.0) {
            throw new IllegalArgumentException("skip must be >= 0.0.");

        }

        XYSeries result = new XYSeries(name);

        if (source.getItemCount(series) > 0) {

            // if the initial averaging period is to be excluded, then
            // calculate the lowest x-value to have an average calculated...
            double first = source.getXValue(series, 0) + skip;

            for (int i = source.getItemCount(series) - 1; i >= 0; i--) {

                // get the current data item...
                double x = source.getXValue(series, i);

                if (x >= first) {
                    // work out the average for the earlier values...
                    int n = 0;
                    double sum = 0.0;
                    double limit = x - period;
                    int offset = 0;
                    boolean finished = false;

                    while (!finished) {
                        if ((i - offset) >= 0) {
                            double xx = source.getXValue(series, i - offset);
                            Number yy = source.getY(series, i - offset);
                            if (xx > limit) {
                                if (yy != null) {
                                    sum = sum + yy.doubleValue();
                                    n = n + 1;
                                }
                            }
                            else {
                                finished = true;
                            }
                        }
                        else {
                            finished = true;
                        }
                        offset = offset + 1;
                    }
                    if (n > 0) {
                        result.add(x, sum / n);
                    }
                    else {
                        result.add(x, null);
                    }
                }

            }
        }

        return result;

    }

}

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