    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 * MeanAndStandardDeviation.java
    029 * -----------------------------
    030 * (C) Copyright 2003-2008, by Object Refinery Limited.
    031 *
    032 * Original Author:  David Gilbert (for Object Refinery Limited);
    033 * Contributor(s):   -;
    034 *
    035 * Changes:
    036 * --------
    037 * 05-Feb-2002 : Version 1 (DG);
    038 * 05-Feb-2005 : Added equals() method and implemented Serializable (DG);
    039 * 02-Oct-2007 : Added getMeanValue() and getStandardDeviationValue() methods
    040 *               for convenience, and toString() method for debugging (DG);
    041 *
    042 */
    043
    044package org.jfree.data.statistics;
    045
    046import java.io.Serializable;
    047
    048import org.jfree.util.ObjectUtilities;
    049
    050/**
    051 * A simple data structure that holds a mean value and a standard deviation
    052 * value.  This is used in the
    053 * {@link org.jfree.data.statistics.DefaultStatisticalCategoryDataset} class.
    054 */
    055public class MeanAndStandardDeviation implements Serializable {
    056
    057    /** For serialization. */
    058    private static final long serialVersionUID = 7413468697315721515L;
    059
    060    /** The mean. */
    061    private Number mean;
    062
    063    /** The standard deviation. */
    064    private Number standardDeviation;
    065
    066    /**
    067     * Creates a new mean and standard deviation record.
    068     *
    069     * @param mean  the mean.
    070     * @param standardDeviation  the standard deviation.
    071     */
    072    public MeanAndStandardDeviation(double mean, double standardDeviation) {
    073        this(new Double(mean), new Double(standardDeviation));
    074    }
    075
    076    /**
    077     * Creates a new mean and standard deviation record.
    078     *
    079     * @param mean  the mean (<code>null</code> permitted).
    080     * @param standardDeviation  the standard deviation (<code>null</code>
    081     *                           permitted.
    082     */
    083    public MeanAndStandardDeviation(Number mean, Number standardDeviation) {
    084        this.mean = mean;
    085        this.standardDeviation = standardDeviation;
    086    }
    087
    088    /**
    089     * Returns the mean.
    090     *
    091     * @return The mean.
    092     */
    093    public Number getMean() {
    094        return this.mean;
    095    }
    096
    097    /**
    098     * Returns the mean as a double primitive.  If the underlying mean is
    099     * <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}