    001    /* ===========================================================
    002     * JFreeChart : a free chart library for the Java(tm) platform
    003     * ===========================================================
    004     *
    005     * (C) Copyright 2000-2008, 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     * [Java is a trademark or registered trademark of Sun Microsystems, Inc.
    025     * in the United States and other countries.]
    026     *
    027     * ----------
    028     * Range.java
    029     * ----------
    030     * (C) Copyright 2002-2008, by Object Refinery Limited and Contributors.
    031     *
    032     * Original Author:  David Gilbert (for Object Refinery Limited);
    033     * Contributor(s):   Chuanhao Chiu;
    034     *                   Bill Kelemen;
    035     *                   Nicolas Brodu;
    036     *                   Sergei Ivanov;
    037     *
    038     * Changes (from 23-Jun-2001)
    039     * --------------------------
    040     * 22-Apr-2002 : Version 1, loosely based by code by Bill Kelemen (DG);
    041     * 30-Apr-2002 : Added getLength() and getCentralValue() methods.  Changed
    042     *               argument check in constructor (DG);
    043     * 13-Jun-2002 : Added contains(double) method (DG);
    044     * 22-Aug-2002 : Added fix to combine method where both ranges are null, thanks
    045     *               to Chuanhao Chiu for reporting and fixing this (DG);
    046     * 07-Oct-2002 : Fixed errors reported by Checkstyle (DG);
    047     * 26-Mar-2003 : Implemented Serializable (DG);
    048     * 14-Aug-2003 : Added equals() method (DG);
    049     * 27-Aug-2003 : Added toString() method (BK);
    050     * 11-Sep-2003 : Added Clone Support (NB);
    051     * 23-Sep-2003 : Fixed Checkstyle issues (DG);
    052     * 25-Sep-2003 : Oops, Range immutable, clone not necessary (NB);
    053     * 05-May-2004 : Added constrain() and intersects() methods (DG);
    054     * 18-May-2004 : Added expand() method (DG);
    055     * ------------- JFreeChart 1.0.x ---------------------------------------------
    056     * 11-Jan-2006 : Added new method expandToInclude(Range, double) (DG);
    057     * 18-Dec-2007 : New methods intersects(Range) and scale(...) thanks to Sergei
    058     *               Ivanov (DG);
    059     *
    060     */
    061
    062    package org.jfree.data;
    063
    064    import java.io.Serializable;
    065
    066    /**
    067     * Represents an immutable range of values.
    068     */
    069    public strictfp class Range implements Serializable {
    070
    071        /** For serialization. */
    072        private static final long serialVersionUID = -906333695431863380L;
    073
    074        /** The lower bound of the range. */
    075        private double lower;
    076
    077        /** The upper bound of the range. */
    078        private double upper;
    079
    080        /**
    081         * Creates a new range.
    082         *
    083         * @param lower  the lower bound (must be <= upper bound).
    084         * @param upper  the upper bound (must be >= lower bound).
    085         */
    086        public Range(double lower, double upper) {
    087            if (lower > upper) {
    088                String msg = "Range(double, double): require lower (" + lower
    089                    + ") <= upper (" + upper + ").";
    090                throw new IllegalArgumentException(msg);
    091            }
    092            this.lower = lower;
    093            this.upper = upper;
    094        }
    095
    096        /**
    097         * Returns the lower bound for the range.
    098         *
    099         * @return The lower bound.
    100         */
    101        public double getLowerBound() {
    102            return this.lower;
    103        }
    104
    105        /**
    106         * Returns the upper bound for the range.
    107         *
    108         * @return The upper bound.
    109         */
    110        public double getUpperBound() {
    111            return this.upper;
    112        }
    113
    114        /**
    115         * Returns the length of the range.
    116         *
    117         * @return The length.
    118         */
    119        public double getLength() {
    120            return this.upper - this.lower;
    121        }
    122
    123        /**
    124         * Returns the central value for the range.
    125         *
    126         * @return The central value.
    127         */
    128        public double getCentralValue() {
    129            return this.lower / 2.0 + this.upper / 2.0;
    130        }
    131
    132        /**
    133         * Returns <code>true</code> if the range contains the specified value and
    134         * <code>false</code> otherwise.
    135         *
    136         * @param value  the value to lookup.
    137         *
    138         * @return <code>true</code> if the range contains the specified value.
    139         */
    140        public boolean contains(double value) {
    141            return (value >= this.lower && value <= this.upper);
    142        }
    143
    144        /**
    145         * Returns <code>true</code> if the range intersects with the specified
    146         * range, and <code>false</code> otherwise.
    147         *
    148         * @param b0  the lower bound (should be <= b1).
    149         * @param b1  the upper bound (should be >= b0).
    150         *
    151         * @return A boolean.
    152         */
    153        public boolean intersects(double b0, double b1) {
    154            if (b0 <= this.lower) {
    155                return (b1 > this.lower);
    156            }
    157            else {
    158                return (b0 < this.upper && b1 >= b0);
    159            }
    160        }
    161
    162        /**
    163         * Returns <code>true</code> if the range intersects with the specified
    164         * range, and <code>false</code> otherwise.
    165         *
    166         * @param range  another range (<code>null</code> not permitted).
    167         *
    168         * @return A boolean.
    169         *
    170         * @since 1.0.9
    171         */
    172        public boolean intersects(Range range) {
    173            return intersects(range.getLowerBound(), range.getUpperBound());
    174        }
    175
    176        /**
    177         * Returns the value within the range that is closest to the specified
    178         * value.
    179         *
    180         * @param value  the value.
    181         *
    182         * @return The constrained value.
    183         */
    184        public double constrain(double value) {
    185            double result = value;
    186            if (!contains(value)) {
    187                if (value > this.upper) {
    188                    result = this.upper;
    189                }
    190                else if (value < this.lower) {
    191                    result = this.lower;
    192                }
    193            }
    194            return result;
    195        }
    196
    197        /**
    198         * Creates a new range by combining two existing ranges.
    199         * <P>
    200         * Note that:
    201         * <ul>
    202         *   <li>either range can be <code>null</code>, in which case the other
    203         *       range is returned;</li>
    204         *   <li>if both ranges are <code>null</code> the return value is
    205         *       <code>null</code>.</li>
    206         * </ul>
    207         *
    208         * @param range1  the first range (<code>null</code> permitted).
    209         * @param range2  the second range (<code>null</code> permitted).
    210         *
    211         * @return A new range (possibly <code>null</code>).
    212         */
    213        public static Range combine(Range range1, Range range2) {
    214            if (range1 == null) {
    215                return range2;
    216            }
    217            else {
    218                if (range2 == null) {
    219                    return range1;
    220                }
    221                else {
    222                    double l = Math.min(range1.getLowerBound(),
    223                            range2.getLowerBound());
    224                    double u = Math.max(range1.getUpperBound(),
    225                            range2.getUpperBound());
    226                    return new Range(l, u);
    227                }
    228            }
    229        }
    230
    231        /**
    232         * Returns a range that includes all the values in the specified
    233         * <code>range</code> AND the specified <code>value</code>.
    234         *
    235         * @param range  the range (<code>null</code> permitted).
    236         * @param value  the value that must be included.
    237         *
    238         * @return A range.
    239         *
    240         * @since 1.0.1
    241         */
    242        public static Range expandToInclude(Range range, double value) {
    243            if (range == null) {
    244                return new Range(value, value);
    245            }
    246            if (value < range.getLowerBound()) {
    247                return new Range(value, range.getUpperBound());
    248            }
    249            else if (value > range.getUpperBound()) {
    250                return new Range(range.getLowerBound(), value);
    251            }
    252            else {
    253                return range;
    254            }
    255        }
    256
    257        /**
    258         * Creates a new range by adding margins to an existing range.
    259         *
    260         * @param range  the range (<code>null</code> not permitted).
    261         * @param lowerMargin  the lower margin (expressed as a percentage of the
    262         *                     range length).
    263         * @param upperMargin  the upper margin (expressed as a percentage of the
    264         *                     range length).
    265         *
    266         * @return The expanded range.
    267         */
    268        public static Range expand(Range range,
    269                                   double lowerMargin, double upperMargin) {
    270            if (range == null) {
    271                throw new IllegalArgumentException("Null 'range' argument.");
    272            }
    273            double length = range.getLength();
    274            double lower = range.getLowerBound() - length * lowerMargin;
    275            double upper = range.getUpperBound() + length * upperMargin;
    276            if (lower > upper) {
    277                lower = lower / 2.0 + upper / 2.0;
    278                upper = lower;
    279            }
    280            return new Range(lower, upper);
    281        }
    282
    283        /**
    284         * Shifts the range by the specified amount.
    285         *
    286         * @param base  the base range (<code>null</code> not permitted).
    287         * @param delta  the shift amount.
    288         *
    289         * @return A new range.
    290         */
    291        public static Range shift(Range base, double delta) {
    292            return shift(base, delta, false);
    293        }
    294
    295        /**
    296         * Shifts the range by the specified amount.
    297         *
    298         * @param base  the base range (<code>null</code> not permitted).
    299         * @param delta  the shift amount.
    300         * @param allowZeroCrossing  a flag that determines whether or not the
    301         *                           bounds of the range are allowed to cross
    302         *                           zero after adjustment.
    303         *
    304         * @return A new range.
    305         */
    306        public static Range shift(Range base, double delta,
    307                                  boolean allowZeroCrossing) {
    308            if (base == null) {
    309                throw new IllegalArgumentException("Null 'base' argument.");
    310            }
    311            if (allowZeroCrossing) {
    312                return new Range(base.getLowerBound() + delta,
    313                        base.getUpperBound() + delta);
    314            }
    315            else {
    316                return new Range(shiftWithNoZeroCrossing(base.getLowerBound(),
    317                        delta), shiftWithNoZeroCrossing(base.getUpperBound(),
    318                        delta));
    319            }
    320        }
    321
    322        /**
    323         * Returns the given <code>value</code> adjusted by <code>delta</code> but
    324         * with a check to prevent the result from crossing <code>0.0</code>.
    325         *
    326         * @param value  the value.
    327         * @param delta  the adjustment.
    328         *
    329         * @return The adjusted value.
    330         */
    331        private static double shiftWithNoZeroCrossing(double value, double delta) {
    332            if (value > 0.0) {
    333                return Math.max(value + delta, 0.0);
    334            }
    335            else if (value < 0.0) {
    336                return Math.min(value + delta, 0.0);
    337            }
    338            else {
    339                return value + delta;
    340            }
    341        }
    342
    343        /**
    344         * Scales the range by the specified factor.
    345         *
    346         * @param base the base range (<code>null</code> not permitted).
    347         * @param factor the scaling factor (must be non-negative).
    348         *
    349         * @return A new range.
    350         *
    351         * @since 1.0.9
    352         */
    353        public static Range scale(Range base, double factor) {
    354            if (base == null) {
    355                throw new IllegalArgumentException("Null 'base' argument.");
    356            }
    357            if (factor < 0) {
    358                throw new IllegalArgumentException("Negative 'factor' argument.");
    359            }
    360            return new Range(base.getLowerBound() * factor,
    361                    base.getUpperBound() * factor);
    362        }
    363
    364        /**
    365         * Tests this object for equality with an arbitrary object.
    366         *
    367         * @param obj  the object to test against (<code>null</code> permitted).
    368         *
    369         * @return A boolean.
    370         */
    371        public boolean equals(Object obj) {
    372            if (!(obj instanceof Range)) {
    373                return false;
    374            }
    375            Range range = (Range) obj;
    376            if (!(this.lower == range.lower)) {
    377                return false;
    378            }
    379            if (!(this.upper == range.upper)) {
    380                return false;
    381            }
    382            return true;
    383        }
    384
    385        /**
    386         * Returns a hash code.
    387         *
    388         * @return A hash code.
    389         */
    390        public int hashCode() {
    391            int result;
    392            long temp;
    393            temp = Double.doubleToLongBits(this.lower);
    394            result = (int) (temp ^ (temp >>> 32));
    395            temp = Double.doubleToLongBits(this.upper);
    396            result = 29 * result + (int) (temp ^ (temp >>> 32));
    397            return result;
    398        }
    399
    400        /**
    401         * Returns a string representation of this Range.
    402         *
    403         * @return A String "Range[lower,upper]" where lower=lower range and
    404         *         upper=upper range.
    405         */
    406        public String toString() {
    407            return ("Range[" + this.lower + "," + this.upper + "]");
    408        }
    409
    410    }