/* ===========================================================
 * JFreeChart : a free chart library for the Java(tm) platform
 * ===========================================================
 *
 * (C) Copyright 2000-2013, by Object Refinery Limited and Contributors.
 *
 * Project Info:  http://www.jfree.org/jfreechart/index.html
 *
 * This library is free software; you can redistribute it and/or modify it
 * under the terms of the GNU Lesser General Public License as published by
 * the Free Software Foundation; either version 2.1 of the License, or
 * (at your option) any later version.
 *
 * This library is distributed in the hope that it will be useful, but
 * WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
 * or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public
 * License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with this library; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301,
 * USA.
 *
 * [Oracle and Java are registered trademarks of Oracle and/or its affiliates. 
 * Other names may be trademarks of their respective owners.]
 *
 * ----------------------------------------
 * DefaultBoxAndWhiskerCategoryDataset.java
 * ----------------------------------------
 * (C) Copyright 2003-2008, by David Browning and Contributors.
 *
 * Original Author:  David Browning (for Australian Institute of Marine
 *                   Science);
 * Contributor(s):   David Gilbert (for Object Refinery Limited);
 *
 * Changes
 * -------
 * 05-Aug-2003 : Version 1, contributed by David Browning (DG);
 * 27-Aug-2003 : Moved from org.jfree.data --> org.jfree.data.statistics (DG);
 * 12-Nov-2003 : Changed 'data' from private to protected and added a new 'add'
 *               method as proposed by Tim Bardzil.  Also removed old code (DG);
 * 01-Mar-2004 : Added equals() method (DG);
 * 18-Nov-2004 : Updates for changes in RangeInfo interface (DG);
 * 11-Jan-2005 : Removed deprecated code in preparation for the 1.0.0
 *               release (DG);
 * ------------- JFREECHART 1.0.x ---------------------------------------------
 * 02-Feb-2007 : Removed author tags from all over JFreeChart sources (DG);
 * 17-Apr-2007 : Fixed bug 1701822 (DG);
 * 13-Jun-2007 : Fixed error in previous patch (DG);
 * 28-Sep-2007 : Fixed cloning bug (DG);
 * 02-Oct-2007 : Fixed bug in updating cached bounds (DG);
 * 03-Oct-2007 : Fixed another bug in updating cached bounds, added removal
 *               methods (DG);
 *
 */

package org.jfree.data.statistics;

import java.util.List;

import org.jfree.data.KeyedObjects2D;
import org.jfree.data.Range;
import org.jfree.data.RangeInfo;
import org.jfree.data.general.AbstractDataset;
import org.jfree.data.general.DatasetChangeEvent;
import org.jfree.util.ObjectUtilities;
import org.jfree.util.PublicCloneable;

/**
 * A convenience class that provides a default implementation of the
 * {@link BoxAndWhiskerCategoryDataset} interface.
 */
public class DefaultBoxAndWhiskerCategoryDataset extends AbstractDataset
        implements BoxAndWhiskerCategoryDataset, RangeInfo, PublicCloneable {

    /** Storage for the data. */
    protected KeyedObjects2D data;

    /** The minimum range value. */
    private double minimumRangeValue;

    /** The row index for the cell that the minimum range value comes from. */
    private int minimumRangeValueRow;

    /**
     * The column index for the cell that the minimum range value comes from.
     */
    private int minimumRangeValueColumn;

    /** The maximum range value. */
    private double maximumRangeValue;

    /** The row index for the cell that the maximum range value comes from. */
    private int maximumRangeValueRow;

    /**
     * The column index for the cell that the maximum range value comes from.
     */
    private int maximumRangeValueColumn;

    /**
     * Creates a new dataset.
     */
    public DefaultBoxAndWhiskerCategoryDataset() {
        this.data = new KeyedObjects2D();
        this.minimumRangeValue = Double.NaN;
        this.minimumRangeValueRow = -1;
        this.minimumRangeValueColumn = -1;
        this.maximumRangeValue = Double.NaN;
        this.maximumRangeValueRow = -1;
        this.maximumRangeValueColumn = -1;
    }

    /**
     * Adds a list of values relating to one box-and-whisker entity to the
     * table.  The various median values are calculated.
     *
     * @param list  a collection of values from which the various medians will
     *              be calculated.
     * @param rowKey  the row key (<code>null</code> not permitted).
     * @param columnKey  the column key (<code>null</code> not permitted).
     *
     * @see #add(BoxAndWhiskerItem, Comparable, Comparable)
     */
    public void add(List list, Comparable rowKey, Comparable columnKey) {
        BoxAndWhiskerItem item = BoxAndWhiskerCalculator
                .calculateBoxAndWhiskerStatistics(list);
        add(item, rowKey, columnKey);
    }

    /**
     * Adds a list of values relating to one Box and Whisker entity to the
     * table.  The various median values are calculated.
     *
     * @param item  a box and whisker item (<code>null</code> not permitted).
     * @param rowKey  the row key (<code>null</code> not permitted).
     * @param columnKey  the column key (<code>null</code> not permitted).
     *
     * @see #add(List, Comparable, Comparable)
     */
    public void add(BoxAndWhiskerItem item, Comparable rowKey,
            Comparable columnKey) {

        this.data.addObject(item, rowKey, columnKey);

        // update cached min and max values
        int r = this.data.getRowIndex(rowKey);
        int c = this.data.getColumnIndex(columnKey);
        if ((this.maximumRangeValueRow == r && this.maximumRangeValueColumn
                == c) || (this.minimumRangeValueRow == r
                && this.minimumRangeValueColumn == c))  {
            updateBounds();
        }
        else {

            double minval = Double.NaN;
            if (item.getMinOutlier() != null) {
                minval = item.getMinOutlier().doubleValue();
            }
            double maxval = Double.NaN;
            if (item.getMaxOutlier() != null) {
                maxval = item.getMaxOutlier().doubleValue();
            }

            if (Double.isNaN(this.maximumRangeValue)) {
                this.maximumRangeValue = maxval;
                this.maximumRangeValueRow = r;
                this.maximumRangeValueColumn = c;
            }
            else if (maxval > this.maximumRangeValue) {
                this.maximumRangeValue = maxval;
                this.maximumRangeValueRow = r;
                this.maximumRangeValueColumn = c;
            }

            if (Double.isNaN(this.minimumRangeValue)) {
                this.minimumRangeValue = minval;
                this.minimumRangeValueRow = r;
                this.minimumRangeValueColumn = c;
            }
            else if (minval < this.minimumRangeValue) {
                this.minimumRangeValue = minval;
                this.minimumRangeValueRow = r;
                this.minimumRangeValueColumn = c;
            }
        }

        fireDatasetChanged();

    }

    /**
     * Removes an item from the dataset and sends a {@link DatasetChangeEvent}
     * to all registered listeners.
     *
     * @param rowKey  the row key (<code>null</code> not permitted).
     * @param columnKey  the column key (<code>null</code> not permitted).
     *
     * @see #add(BoxAndWhiskerItem, Comparable, Comparable)
     *
     * @since 1.0.7
     */
    public void remove(Comparable rowKey, Comparable columnKey) {
        // defer null argument checks
        int r = getRowIndex(rowKey);
        int c = getColumnIndex(columnKey);
        this.data.removeObject(rowKey, columnKey);

        // if this cell held a maximum and/or minimum value, we'll need to
        // update the cached bounds...
        if ((this.maximumRangeValueRow == r && this.maximumRangeValueColumn
                == c) || (this.minimumRangeValueRow == r
                && this.minimumRangeValueColumn == c))  {
            updateBounds();
        }

        fireDatasetChanged();
    }

    /**
     * Removes a row from the dataset and sends a {@link DatasetChangeEvent}
     * to all registered listeners.
     *
     * @param rowIndex  the row index.
     *
     * @see #removeColumn(int)
     *
     * @since 1.0.7
     */
    public void removeRow(int rowIndex) {
        this.data.removeRow(rowIndex);
        updateBounds();
        fireDatasetChanged();
    }

    /**
     * Removes a row from the dataset and sends a {@link DatasetChangeEvent}
     * to all registered listeners.
     *
     * @param rowKey  the row key.
     *
     * @see #removeColumn(Comparable)
     *
     * @since 1.0.7
     */
    public void removeRow(Comparable rowKey) {
        this.data.removeRow(rowKey);
        updateBounds();
        fireDatasetChanged();
    }

    /**
     * Removes a column from the dataset and sends a {@link DatasetChangeEvent}
     * to all registered listeners.
     *
     * @param columnIndex  the column index.
     *
     * @see #removeRow(int)
     *
     * @since 1.0.7
     */
    public void removeColumn(int columnIndex) {
        this.data.removeColumn(columnIndex);
        updateBounds();
        fireDatasetChanged();
    }

    /**
     * Removes a column from the dataset and sends a {@link DatasetChangeEvent}
     * to all registered listeners.
     *
     * @param columnKey  the column key.
     *
     * @see #removeRow(Comparable)
     *
     * @since 1.0.7
     */
    public void removeColumn(Comparable columnKey) {
        this.data.removeColumn(columnKey);
        updateBounds();
        fireDatasetChanged();
    }

    /**
     * Clears all data from the dataset and sends a {@link DatasetChangeEvent}
     * to all registered listeners.
     *
     * @since 1.0.7
     */
    public void clear() {
        this.data.clear();
        updateBounds();
        fireDatasetChanged();
    }

    /**
     * Return an item from within the dataset.
     *
     * @param row  the row index.
     * @param column  the column index.
     *
     * @return The item.
     */
    public BoxAndWhiskerItem getItem(int row, int column) {
        return (BoxAndWhiskerItem) this.data.getObject(row, column);
    }

    /**
     * Returns the value for an item.
     *
     * @param row  the row index.
     * @param column  the column index.
     *
     * @return The value.
     *
     * @see #getMedianValue(int, int)
     * @see #getValue(Comparable, Comparable)
     */
    @Override
    public Number getValue(int row, int column) {
        return getMedianValue(row, column);
    }

    /**
     * Returns the value for an item.
     *
     * @param rowKey  the row key.
     * @param columnKey  the columnKey.
     *
     * @return The value.
     *
     * @see #getMedianValue(Comparable, Comparable)
     * @see #getValue(int, int)
     */
    @Override
    public Number getValue(Comparable rowKey, Comparable columnKey) {
        return getMedianValue(rowKey, columnKey);
    }

    /**
     * Returns the mean value for an item.
     *
     * @param row  the row index (zero-based).
     * @param column  the column index (zero-based).
     *
     * @return The mean value.
     *
     * @see #getItem(int, int)
     */
    @Override
    public Number getMeanValue(int row, int column) {

        Number result = null;
        BoxAndWhiskerItem item = (BoxAndWhiskerItem) this.data.getObject(row,
                column);
        if (item != null) {
            result = item.getMean();
        }
        return result;

    }

    /**
     * Returns the mean value for an item.
     *
     * @param rowKey  the row key.
     * @param columnKey  the column key.
     *
     * @return The mean value.
     *
     * @see #getItem(int, int)
     */
    @Override
    public Number getMeanValue(Comparable rowKey, Comparable columnKey) {
        Number result = null;
        BoxAndWhiskerItem item = (BoxAndWhiskerItem) this.data.getObject(
                rowKey, columnKey);
        if (item != null) {
            result = item.getMean();
        }
        return result;
    }

    /**
     * Returns the median value for an item.
     *
     * @param row  the row index (zero-based).
     * @param column  the column index (zero-based).
     *
     * @return The median value.
     *
     * @see #getItem(int, int)
     */
    @Override
    public Number getMedianValue(int row, int column) {
        Number result = null;
        BoxAndWhiskerItem item = (BoxAndWhiskerItem) this.data.getObject(row,
                column);
        if (item != null) {
            result = item.getMedian();
        }
        return result;
    }

    /**
     * Returns the median value for an item.
     *
     * @param rowKey  the row key.
     * @param columnKey  the columnKey.
     *
     * @return The median value.
     *
     * @see #getItem(int, int)
     */
    @Override
    public Number getMedianValue(Comparable rowKey, Comparable columnKey) {
        Number result = null;
        BoxAndWhiskerItem item = (BoxAndWhiskerItem) this.data.getObject(
                rowKey, columnKey);
        if (item != null) {
            result = item.getMedian();
        }
        return result;
    }

    /**
     * Returns the first quartile value.
     *
     * @param row  the row index (zero-based).
     * @param column  the column index (zero-based).
     *
     * @return The first quartile value.
     *
     * @see #getItem(int, int)
     */
    @Override
    public Number getQ1Value(int row, int column) {
        Number result = null;
        BoxAndWhiskerItem item = (BoxAndWhiskerItem) this.data.getObject(
                row, column);
        if (item != null) {
            result = item.getQ1();
        }
        return result;
    }

    /**
     * Returns the first quartile value.
     *
     * @param rowKey  the row key.
     * @param columnKey  the column key.
     *
     * @return The first quartile value.
     *
     * @see #getItem(int, int)
     */
    @Override
    public Number getQ1Value(Comparable rowKey, Comparable columnKey) {
        Number result = null;
        BoxAndWhiskerItem item = (BoxAndWhiskerItem) this.data.getObject(
                rowKey, columnKey);
        if (item != null) {
            result = item.getQ1();
        }
        return result;
    }

    /**
     * Returns the third quartile value.
     *
     * @param row  the row index (zero-based).
     * @param column  the column index (zero-based).
     *
     * @return The third quartile value.
     *
     * @see #getItem(int, int)
     */
    @Override
    public Number getQ3Value(int row, int column) {
        Number result = null;
        BoxAndWhiskerItem item = (BoxAndWhiskerItem) this.data.getObject(
                row, column);
        if (item != null) {
            result = item.getQ3();
        }
        return result;
    }

    /**
     * Returns the third quartile value.
     *
     * @param rowKey  the row key.
     * @param columnKey  the column key.
     *
     * @return The third quartile value.
     *
     * @see #getItem(int, int)
     */
    @Override
    public Number getQ3Value(Comparable rowKey, Comparable columnKey) {
        Number result = null;
        BoxAndWhiskerItem item = (BoxAndWhiskerItem) this.data.getObject(
                rowKey, columnKey);
        if (item != null) {
            result = item.getQ3();
        }
        return result;
    }

    /**
     * Returns the column index for a given key.
     *
     * @param key  the column key (<code>null</code> not permitted).
     *
     * @return The column index.
     *
     * @see #getColumnKey(int)
     */
    @Override
    public int getColumnIndex(Comparable key) {
        return this.data.getColumnIndex(key);
    }

    /**
     * Returns a column key.
     *
     * @param column  the column index (zero-based).
     *
     * @return The column key.
     *
     * @see #getColumnIndex(Comparable)
     */
    @Override
    public Comparable getColumnKey(int column) {
        return this.data.getColumnKey(column);
    }

    /**
     * Returns the column keys.
     *
     * @return The keys.
     *
     * @see #getRowKeys()
     */
    @Override
    public List getColumnKeys() {
        return this.data.getColumnKeys();
    }

    /**
     * Returns the row index for a given key.
     *
     * @param key  the row key (<code>null</code> not permitted).
     *
     * @return The row index.
     *
     * @see #getRowKey(int)
     */
    @Override
    public int getRowIndex(Comparable key) {
        // defer null argument check
        return this.data.getRowIndex(key);
    }

    /**
     * Returns a row key.
     *
     * @param row  the row index (zero-based).
     *
     * @return The row key.
     *
     * @see #getRowIndex(Comparable)
     */
    @Override
    public Comparable getRowKey(int row) {
        return this.data.getRowKey(row);
    }

    /**
     * Returns the row keys.
     *
     * @return The keys.
     *
     * @see #getColumnKeys()
     */
    @Override
    public List getRowKeys() {
        return this.data.getRowKeys();
    }

    /**
     * Returns the number of rows in the table.
     *
     * @return The row count.
     *
     * @see #getColumnCount()
     */
    @Override
    public int getRowCount() {
        return this.data.getRowCount();
    }

    /**
     * Returns the number of columns in the table.
     *
     * @return The column count.
     *
     * @see #getRowCount()
     */
    @Override
    public int getColumnCount() {
        return this.data.getColumnCount();
    }

    /**
     * Returns the minimum y-value in the dataset.
     *
     * @param includeInterval  a flag that determines whether or not the
     *                         y-interval is taken into account.
     *
     * @return The minimum value.
     *
     * @see #getRangeUpperBound(boolean)
     */
    @Override
    public double getRangeLowerBound(boolean includeInterval) {
        return this.minimumRangeValue;
    }

    /**
     * Returns the maximum y-value in the dataset.
     *
     * @param includeInterval  a flag that determines whether or not the
     *                         y-interval is taken into account.
     *
     * @return The maximum value.
     *
     * @see #getRangeLowerBound(boolean)
     */
    @Override
    public double getRangeUpperBound(boolean includeInterval) {
        return this.maximumRangeValue;
    }

    /**
     * Returns the range of the values in this dataset's range.
     *
     * @param includeInterval  a flag that determines whether or not the
     *                         y-interval is taken into account.
     *
     * @return The range.
     */
    @Override
    public Range getRangeBounds(boolean includeInterval) {
        return new Range(this.minimumRangeValue, this.maximumRangeValue);
    }

    /**
     * Returns the minimum regular (non outlier) value for an item.
     *
     * @param row  the row index (zero-based).
     * @param column  the column index (zero-based).
     *
     * @return The minimum regular value.
     *
     * @see #getItem(int, int)
     */
    @Override
    public Number getMinRegularValue(int row, int column) {
        Number result = null;
        BoxAndWhiskerItem item = (BoxAndWhiskerItem) this.data.getObject(
                row, column);
        if (item != null) {
            result = item.getMinRegularValue();
        }
        return result;
    }

    /**
     * Returns the minimum regular (non outlier) value for an item.
     *
     * @param rowKey  the row key.
     * @param columnKey  the column key.
     *
     * @return The minimum regular value.
     *
     * @see #getItem(int, int)
     */
    @Override
    public Number getMinRegularValue(Comparable rowKey, Comparable columnKey) {
        Number result = null;
        BoxAndWhiskerItem item = (BoxAndWhiskerItem) this.data.getObject(
                rowKey, columnKey);
        if (item != null) {
            result = item.getMinRegularValue();
        }
        return result;
    }

    /**
     * Returns the maximum regular (non outlier) value for an item.
     *
     * @param row  the row index (zero-based).
     * @param column  the column index (zero-based).
     *
     * @return The maximum regular value.
     *
     * @see #getItem(int, int)
     */
    @Override
    public Number getMaxRegularValue(int row, int column) {
        Number result = null;
        BoxAndWhiskerItem item = (BoxAndWhiskerItem) this.data.getObject(
                row, column);
        if (item != null) {
            result = item.getMaxRegularValue();
        }
        return result;
    }

    /**
     * Returns the maximum regular (non outlier) value for an item.
     *
     * @param rowKey  the row key.
     * @param columnKey  the column key.
     *
     * @return The maximum regular value.
     *
     * @see #getItem(int, int)
     */
    @Override
    public Number getMaxRegularValue(Comparable rowKey, Comparable columnKey) {
        Number result = null;
        BoxAndWhiskerItem item = (BoxAndWhiskerItem) this.data.getObject(
                rowKey, columnKey);
        if (item != null) {
            result = item.getMaxRegularValue();
        }
        return result;
    }

    /**
     * Returns the minimum outlier (non farout) value for an item.
     *
     * @param row  the row index (zero-based).
     * @param column  the column index (zero-based).
     *
     * @return The minimum outlier.
     *
     * @see #getItem(int, int)
     */
    @Override
    public Number getMinOutlier(int row, int column) {
        Number result = null;
        BoxAndWhiskerItem item = (BoxAndWhiskerItem) this.data.getObject(
                row, column);
        if (item != null) {
            result = item.getMinOutlier();
        }
        return result;
    }

    /**
     * Returns the minimum outlier (non farout) value for an item.
     *
     * @param rowKey  the row key.
     * @param columnKey  the column key.
     *
     * @return The minimum outlier.
     *
     * @see #getItem(int, int)
     */
    @Override
    public Number getMinOutlier(Comparable rowKey, Comparable columnKey) {
        Number result = null;
        BoxAndWhiskerItem item = (BoxAndWhiskerItem) this.data.getObject(
                rowKey, columnKey);
        if (item != null) {
            result = item.getMinOutlier();
        }
        return result;
    }

    /**
     * Returns the maximum outlier (non farout) value for an item.
     *
     * @param row  the row index (zero-based).
     * @param column  the column index (zero-based).
     *
     * @return The maximum outlier.
     *
     * @see #getItem(int, int)
     */
    @Override
    public Number getMaxOutlier(int row, int column) {
        Number result = null;
        BoxAndWhiskerItem item = (BoxAndWhiskerItem) this.data.getObject(
                row, column);
        if (item != null) {
            result = item.getMaxOutlier();
        }
        return result;
    }

    /**
     * Returns the maximum outlier (non farout) value for an item.
     *
     * @param rowKey  the row key.
     * @param columnKey  the column key.
     *
     * @return The maximum outlier.
     *
     * @see #getItem(int, int)
     */
    @Override
    public Number getMaxOutlier(Comparable rowKey, Comparable columnKey) {
        Number result = null;
        BoxAndWhiskerItem item = (BoxAndWhiskerItem) this.data.getObject(
                rowKey, columnKey);
        if (item != null) {
            result = item.getMaxOutlier();
        }
        return result;
    }

    /**
     * Returns a list of outlier values for an item.
     *
     * @param row  the row index (zero-based).
     * @param column  the column index (zero-based).
     *
     * @return A list of outlier values.
     *
     * @see #getItem(int, int)
     */
    @Override
    public List getOutliers(int row, int column) {
        List result = null;
        BoxAndWhiskerItem item = (BoxAndWhiskerItem) this.data.getObject(
                row, column);
        if (item != null) {
            result = item.getOutliers();
        }
        return result;
    }

    /**
     * Returns a list of outlier values for an item.
     *
     * @param rowKey  the row key.
     * @param columnKey  the column key.
     *
     * @return A list of outlier values.
     *
     * @see #getItem(int, int)
     */
    @Override
    public List getOutliers(Comparable rowKey, Comparable columnKey) {
        List result = null;
        BoxAndWhiskerItem item = (BoxAndWhiskerItem) this.data.getObject(
                rowKey, columnKey);
        if (item != null) {
            result = item.getOutliers();
        }
        return result;
    }

    /**
     * Resets the cached bounds, by iterating over the entire dataset to find
     * the current bounds.
     */
    private void updateBounds() {
        this.minimumRangeValue = Double.NaN;
        this.minimumRangeValueRow = -1;
        this.minimumRangeValueColumn = -1;
        this.maximumRangeValue = Double.NaN;
        this.maximumRangeValueRow = -1;
        this.maximumRangeValueColumn = -1;
        int rowCount = getRowCount();
        int columnCount = getColumnCount();
        for (int r = 0; r < rowCount; r++) {
            for (int c = 0; c < columnCount; c++) {
                BoxAndWhiskerItem item = getItem(r, c);
                if (item != null) {
                    Number min = item.getMinOutlier();
                    if (min != null) {
                        double minv = min.doubleValue();
                        if (!Double.isNaN(minv)) {
                            if (minv < this.minimumRangeValue || Double.isNaN(
                                    this.minimumRangeValue)) {
                                this.minimumRangeValue = minv;
                                this.minimumRangeValueRow = r;
                                this.minimumRangeValueColumn = c;
                            }
                        }
                    }
                    Number max = item.getMaxOutlier();
                    if (max != null) {
                        double maxv = max.doubleValue();
                        if (!Double.isNaN(maxv)) {
                            if (maxv > this.maximumRangeValue || Double.isNaN(
                                    this.maximumRangeValue)) {
                                this.maximumRangeValue = maxv;
                                this.maximumRangeValueRow = r;
                                this.maximumRangeValueColumn = c;
                            }
                        }
                    }
                }
            }
        }
    }

    /**
     * Tests this dataset for equality with an arbitrary object.
     *
     * @param obj  the object to test against (<code>null</code> permitted).
     *
     * @return A boolean.
     */
    @Override
    public boolean equals(Object obj) {
        if (obj == this) {
            return true;
        }
        if (obj instanceof DefaultBoxAndWhiskerCategoryDataset) {
            DefaultBoxAndWhiskerCategoryDataset dataset
                    = (DefaultBoxAndWhiskerCategoryDataset) obj;
            return ObjectUtilities.equal(this.data, dataset.data);
        }
        return false;
    }

    /**
     * Returns a clone of this dataset.
     *
     * @return A clone.
     *
     * @throws CloneNotSupportedException if cloning is not possible.
     */
    @Override
    public Object clone() throws CloneNotSupportedException {
        DefaultBoxAndWhiskerCategoryDataset clone
                = (DefaultBoxAndWhiskerCategoryDataset) super.clone();
        clone.data = (KeyedObjects2D) this.data.clone();
        return clone;
    }

}