Source for org.jfree.data.statistics.MeanAndStandardDeviation

   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:  * MeanAndStandardDeviation.java
  29:  * -----------------------------
  30:  * (C) Copyright 2003-2007, by Object Refinery Limited.
  31:  *
  32:  * Original Author:  David Gilbert (for Object Refinery Limited);
  33:  * Contributor(s):   -;
  34:  *
  35:  * Changes:
  36:  * --------
  37:  * 05-Feb-2002 : Version 1 (DG);
  38:  * 05-Feb-2005 : Added equals() method and implemented Serializable (DG);
  39:  * 02-Oct-2007 : Added getMeanValue() and getStandardDeviationValue() methods
  40:  *               for convenience, and toString() method for debugging (DG);
  41:  *
  42:  */
  43: 
  44: package org.jfree.data.statistics;
  45: 
  46: import java.io.Serializable;
  47: 
  48: import org.jfree.util.ObjectUtilities;
  49: 
  50: /**
  51:  * A simple data structure that holds a mean value and a standard deviation 
  52:  * value.  This is used in the 
  53:  * {@link org.jfree.data.statistics.DefaultStatisticalCategoryDataset} class.
  54:  */
  55: public class MeanAndStandardDeviation implements Serializable {
  56: 
  57:     /** For serialization. */
  58:     private static final long serialVersionUID = 7413468697315721515L;
  59:     
  60:     /** The mean. */
  61:     private Number mean;
  62: 
  63:     /** The standard deviation. */
  64:     private Number standardDeviation;
  65: 
  66:     /**
  67:      * Creates a new mean and standard deviation record.
  68:      * 
  69:      * @param mean  the mean.
  70:      * @param standardDeviation  the standard deviation.
  71:      */
  72:     public MeanAndStandardDeviation(double mean, double standardDeviation) {
  73:         this(new Double(mean), new Double(standardDeviation));   
  74:     }
  75:     
  76:     /**
  77:      * Creates a new mean and standard deviation record.
  78:      *
  79:      * @param mean  the mean (<code>null</code> permitted).
  80:      * @param standardDeviation  the standard deviation (<code>null</code>
  81:      *                           permitted.
  82:      */
  83:     public MeanAndStandardDeviation(Number mean, Number standardDeviation) {
  84:         this.mean = mean;
  85:         this.standardDeviation = standardDeviation;
  86:     }
  87: 
  88:     /**
  89:      * Returns the mean.
  90:      *
  91:      * @return The mean.
  92:      */
  93:     public Number getMean() {
  94:         return this.mean;
  95:     }
  96:     
  97:     /**
  98:      * Returns the mean as a double primitive.  If the underlying mean is
  99:      * <code>null</code>, this method will return <code>Double.NaN</code>.
 100:      * 
 101:      * @return The mean.
 102:      * 
 103:      * @see #getMean()
 104:      * 
 105:      * @since 1.0.7
 106:      */
 107:     public double getMeanValue() {
 108:         double result = Double.NaN;
 109:         if (this.mean != null) {
 110:             result = this.mean.doubleValue();
 111:         }
 112:         return result;
 113:     }
 114: 
 115:     /**
 116:      * Returns the standard deviation.
 117:      *
 118:      * @return The standard deviation.
 119:      */
 120:     public Number getStandardDeviation() {
 121:         return this.standardDeviation;
 122:     }
 123: 
 124:     /**
 125:      * Returns the standard deviation as a double primitive.  If the underlying
 126:      * standard deviation is <code>null</code>, this method will return 
 127:      * <code>Double.NaN</code>.
 128:      * 
 129:      * @return The standard deviation.
 130:      * 
 131:      * @since 1.0.7
 132:      */
 133:     public double getStandardDeviationValue() {
 134:         double result = Double.NaN;
 135:         if (this.standardDeviation != null) {
 136:             result = this.standardDeviation.doubleValue();
 137:         }
 138:         return result;
 139:     }
 140: 
 141:     /**
 142:      * Tests this instance for equality with an arbitrary object.
 143:      * 
 144:      * @param obj  the object (<code>null</code> permitted).
 145:      * 
 146:      * @return A boolean.
 147:      */
 148:     public boolean equals(Object obj) {
 149:         if (obj == this) {
 150:             return true;   
 151:         }
 152:         if (!(obj instanceof MeanAndStandardDeviation)) {
 153:             return false;   
 154:         }
 155:         MeanAndStandardDeviation that = (MeanAndStandardDeviation) obj;
 156:         if (!ObjectUtilities.equal(this.mean, that.mean)) {
 157:             return false;   
 158:         }
 159:         if (!ObjectUtilities.equal(
 160:             this.standardDeviation, that.standardDeviation)
 161:         ) {
 162:             return false;   
 163:         }
 164:         return true;
 165:     }
 166:     
 167:     /**
 168:      * Returns a string representing this instance.
 169:      * 
 170:      * @return A string.
 171:      * 
 172:      * @since 1.0.7
 173:      */
 174:     public String toString() {
 175:         return "[" + this.mean + ", " + this.standardDeviation + "]";
 176:     }
 177: 
 178: }