    001/* ===========================================================
    002 * JFreeChart : a free chart library for the Java(tm) platform
    003 * ===========================================================
    004 *
    005 * (C) Copyright 2000-2011, by Object Refinery Limited and Contributors.
    006 *
    007 * Project Info:  http://www.jfree.org/jfreechart/index.html
    008 *
    009 * This library is free software; you can redistribute it and/or modify it
    010 * under the terms of the GNU Lesser General Public License as published by
    011 * the Free Software Foundation; either version 2.1 of the License, or
    012 * (at your option) any later version.
    013 *
    014 * This library is distributed in the hope that it will be useful, but
    015 * WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
    016 * or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public
    017 * License for more details.
    018 *
    019 * You should have received a copy of the GNU Lesser General Public
    020 * License along with this library; if not, write to the Free Software
    021 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301,
    022 * USA.
    023 *
    024 * [Oracle and Java are registered trademarks of Oracle and/or its affiliates.
    025 * Other names may be trademarks of their respective owners.]
    026 *
    027 * ----------------------------
    028 * BoxAndWhiskerCalculator.java
    029 * ----------------------------
    030 * (C) Copyright 2003-2008,  by Object Refinery Limited and Contributors.
    031 *
    032 * Original Author:  David Gilbert (for Object Refinery Limited);
    033 * Contributor(s):   -;
    034 *
    035 * Changes
    036 * -------
    037 * 28-Aug-2003 : Version 1 (DG);
    038 * 17-Nov-2003 : Fixed bug in calculations of outliers and median (DG);
    039 * 10-Jan-2005 : Removed deprecated methods in preparation for 1.0.0
    040 *               release (DG);
    041 * ------------- JFREECHART 1.0.x ---------------------------------------------
    042 * 15-Nov-2006 : Cleaned up handling of null arguments, and null or NaN items
    043 *               in the list (DG);
    044 *
    045 */
    046
    047package org.jfree.data.statistics;
    048
    049import java.util.ArrayList;
    050import java.util.Collections;
    051import java.util.Iterator;
    052import java.util.List;
    053
    054/**
    055 * A utility class that calculates the mean, median, quartiles Q1 and Q3, plus
    056 * a list of outlier values...all from an arbitrary list of
    057 * <code>Number</code> objects.
    058 */
    059public abstract class BoxAndWhiskerCalculator {
    060
    061    /**
    062     * Calculates the statistics required for a {@link BoxAndWhiskerItem}
    063     * from a list of <code>Number</code> objects.  Any items in the list
    064     * that are <code>null</code>, not an instance of <code>Number</code>, or
    065     * equivalent to <code>Double.NaN</code>, will be ignored.
    066     *
    067     * @param values  a list of numbers (a <code>null</code> list is not
    068     *                permitted).
    069     *
    070     * @return A box-and-whisker item.
    071     */
    072    public static BoxAndWhiskerItem calculateBoxAndWhiskerStatistics(
    073                                        List values) {
    074        return calculateBoxAndWhiskerStatistics(values, true);
    075    }
    076
    077    /**
    078     * Calculates the statistics required for a {@link BoxAndWhiskerItem}
    079     * from a list of <code>Number</code> objects.  Any items in the list
    080     * that are <code>null</code>, not an instance of <code>Number</code>, or
    081     * equivalent to <code>Double.NaN</code>, will be ignored.
    082     *
    083     * @param values  a list of numbers (a <code>null</code> list is not
    084     *                permitted).
    085     * @param stripNullAndNaNItems  a flag that controls the handling of null
    086     *     and NaN items.
    087     *
    088     * @return A box-and-whisker item.
    089     *
    090     * @since 1.0.3
    091     */
    092    public static BoxAndWhiskerItem calculateBoxAndWhiskerStatistics(
    093            List values, boolean stripNullAndNaNItems) {
    094
    095        if (values == null) {
    096            throw new IllegalArgumentException("Null 'values' argument.");
    097        }
    098
    099        List vlist;
    100        if (stripNullAndNaNItems) {
    101            vlist = new ArrayList(values.size());
    102            Iterator iterator = values.listIterator();
    103            while (iterator.hasNext()) {
    104                Object obj = iterator.next();
    105                if (obj instanceof Number) {
    106                    Number n = (Number) obj;
    107                    double v = n.doubleValue();
    108                    if (!Double.isNaN(v)) {
    109                        vlist.add(n);
    110                    }
    111                }
    112            }
    113        }
    114        else {
    115            vlist = values;
    116        }
    117        Collections.sort(vlist);
    118
    119        double mean = Statistics.calculateMean(vlist, false);
    120        double median = Statistics.calculateMedian(vlist, false);
    121        double q1 = calculateQ1(vlist);
    122        double q3 = calculateQ3(vlist);
    123
    124        double interQuartileRange = q3 - q1;
    125
    126        double upperOutlierThreshold = q3 + (interQuartileRange * 1.5);
    127        double lowerOutlierThreshold = q1 - (interQuartileRange * 1.5);
    128
    129        double upperFaroutThreshold = q3 + (interQuartileRange * 2.0);
    130        double lowerFaroutThreshold = q1 - (interQuartileRange * 2.0);
    131
    132        double minRegularValue = Double.POSITIVE_INFINITY;
    133        double maxRegularValue = Double.NEGATIVE_INFINITY;
    134        double minOutlier = Double.POSITIVE_INFINITY;
    135        double maxOutlier = Double.NEGATIVE_INFINITY;
    136        List outliers = new ArrayList();
    137
    138        Iterator iterator = vlist.iterator();
    139        while (iterator.hasNext()) {
    140            Number number = (Number) iterator.next();
    141            double value = number.doubleValue();
    142            if (value > upperOutlierThreshold) {
    143                outliers.add(number);
    144                if (value > maxOutlier && value <= upperFaroutThreshold) {
    145                    maxOutlier = value;
    146                }
    147            }
    148            else if (value < lowerOutlierThreshold) {
    149                outliers.add(number);
    150                if (value < minOutlier && value >= lowerFaroutThreshold) {
    151                    minOutlier = value;
    152                }
    153            }
    154            else {
    155                minRegularValue = Math.min(minRegularValue, value);
    156                maxRegularValue = Math.max(maxRegularValue, value);
    157            }
    158            minOutlier = Math.min(minOutlier, minRegularValue);
    159            maxOutlier = Math.max(maxOutlier, maxRegularValue);
    160        }
    161
    162        return new BoxAndWhiskerItem(new Double(mean), new Double(median),
    163                new Double(q1), new Double(q3), new Double(minRegularValue),
    164                new Double(maxRegularValue), new Double(minOutlier),
    165                new Double(maxOutlier), outliers);
    166
    167    }
    168
    169    /**
    170     * Calculates the first quartile for a list of numbers in ascending order.
    171     * If the items in the list are not in ascending order, the result is
    172     * unspecified.  If the list contains items that are <code>null</code>, not
    173     * an instance of <code>Number</code>, or equivalent to
    174     * <code>Double.NaN</code>, the result is unspecified.
    175     *
    176     * @param values  the numbers in ascending order (<code>null</code> not
    177     *     permitted).
    178     *
    179     * @return The first quartile.
    180     */
    181    public static double calculateQ1(List values) {
    182        if (values == null) {
    183            throw new IllegalArgumentException("Null 'values' argument.");
    184        }
    185
    186        double result = Double.NaN;
    187        int count = values.size();
    188        if (count > 0) {
    189            if (count % 2 == 1) {
    190                if (count > 1) {
    191                    result = Statistics.calculateMedian(values, 0, count / 2);
    192                }
    193                else {
    194                    result = Statistics.calculateMedian(values, 0, 0);
    195                }
    196            }
    197            else {
    198                result = Statistics.calculateMedian(values, 0, count / 2 - 1);
    199            }
    200
    201        }
    202        return result;
    203    }
    204
    205    /**
    206     * Calculates the third quartile for a list of numbers in ascending order.
    207     * If the items in the list are not in ascending order, the result is
    208     * unspecified.  If the list contains items that are <code>null</code>, not
    209     * an instance of <code>Number</code>, or equivalent to
    210     * <code>Double.NaN</code>, the result is unspecified.
    211     *
    212     * @param values  the list of values (<code>null</code> not permitted).
    213     *
    214     * @return The third quartile.
    215     */
    216    public static double calculateQ3(List values) {
    217        if (values == null) {
    218            throw new IllegalArgumentException("Null 'values' argument.");
    219        }
    220        double result = Double.NaN;
    221        int count = values.size();
    222        if (count > 0) {
    223            if (count % 2 == 1) {
    224                if (count > 1) {
    225                    result = Statistics.calculateMedian(values, count / 2,
    226                            count - 1);
    227                }
    228                else {
    229                    result = Statistics.calculateMedian(values, 0, 0);
    230                }
    231            }
    232            else {
    233                result = Statistics.calculateMedian(values, count / 2,
    234                        count - 1);
    235            }
    236        }
    237        return result;
    238    }
    239
    240}