Source for org.jfree.data.statistics.BoxAndWhiskerCalculator

   1: /* ===========================================================
   2:  * JFreeChart : a free chart library for the Java(tm) platform
   3:  * ===========================================================
   4:  *
   5:  * (C) Copyright 2000-2007, by Object Refinery Limited and Contributors.
   6:  *
   7:  * Project Info:  http://www.jfree.org/jfreechart/index.html
   8:  *
   9:  * This library is free software; you can redistribute it and/or modify it 
  10:  * under the terms of the GNU Lesser General Public License as published by 
  11:  * the Free Software Foundation; either version 2.1 of the License, or 
  12:  * (at your option) any later version.
  13:  *
  14:  * This library is distributed in the hope that it will be useful, but 
  15:  * WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY 
  16:  * or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public 
  17:  * License for more details.
  18:  *
  19:  * You should have received a copy of the GNU Lesser General Public
  20:  * License along with this library; if not, write to the Free Software
  21:  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, 
  22:  * USA.  
  23:  *
  24:  * [Java is a trademark or registered trademark of Sun Microsystems, Inc. 
  25:  * in the United States and other countries.]
  26:  *
  27:  * ----------------------------
  28:  * BoxAndWhiskerCalculator.java
  29:  * ----------------------------
  30:  * (C) Copyright 2003-2007,  by Object Refinery Limited and Contributors.
  31:  *
  32:  * Original Author:  David Gilbert (for Object Refinery Limited);
  33:  * Contributor(s):   -;
  34:  *
  35:  * Changes
  36:  * -------
  37:  * 28-Aug-2003 : Version 1 (DG);
  38:  * 17-Nov-2003 : Fixed bug in calculations of outliers and median (DG);
  39:  * 10-Jan-2005 : Removed deprecated methods in preparation for 1.0.0 
  40:  *               release (DG);
  41:  * ------------- JFREECHART 1.0.x ---------------------------------------------
  42:  * 15-Nov-2006 : Cleaned up handling of null arguments, and null or NaN items 
  43:  *               in the list (DG);
  44:  *
  45:  */
  46: 
  47: package org.jfree.data.statistics;
  48: 
  49: import java.util.ArrayList;
  50: import java.util.Collections;
  51: import java.util.Iterator;
  52: import java.util.List;
  53: 
  54: /**
  55:  * A utility class that calculates the mean, median, quartiles Q1 and Q3, plus
  56:  * a list of outlier values...all from an arbitrary list of 
  57:  * <code>Number</code> objects.
  58:  */
  59: public abstract class BoxAndWhiskerCalculator {
  60:     
  61:     /**
  62:      * Calculates the statistics required for a {@link BoxAndWhiskerItem}
  63:      * from a list of <code>Number</code> objects.  Any items in the list
  64:      * that are <code>null</code>, not an instance of <code>Number</code>, or
  65:      * equivalent to <code>Double.NaN</code>, will be ignored.
  66:      * 
  67:      * @param values  a list of numbers (a <code>null</code> list is not 
  68:      *                permitted).
  69:      * 
  70:      * @return A box-and-whisker item.
  71:      */
  72:     public static BoxAndWhiskerItem calculateBoxAndWhiskerStatistics(
  73:                                         List values) {
  74:         return calculateBoxAndWhiskerStatistics(values, true); 
  75:     }
  76: 
  77:     /**
  78:      * Calculates the statistics required for a {@link BoxAndWhiskerItem}
  79:      * from a list of <code>Number</code> objects.  Any items in the list
  80:      * that are <code>null</code>, not an instance of <code>Number</code>, or
  81:      * equivalent to <code>Double.NaN</code>, will be ignored.
  82:      * 
  83:      * @param values  a list of numbers (a <code>null</code> list is not 
  84:      *                permitted).
  85:      * @param stripNullAndNaNItems  a flag that controls the handling of null
  86:      *     and NaN items.
  87:      * 
  88:      * @return A box-and-whisker item.
  89:      * 
  90:      * @since 1.0.3
  91:      */
  92:     public static BoxAndWhiskerItem calculateBoxAndWhiskerStatistics(
  93:             List values, boolean stripNullAndNaNItems) {
  94:         
  95:         if (values == null) { 
  96:             throw new IllegalArgumentException("Null 'values' argument.");
  97:         }
  98:         
  99:         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: }