* @param item  the item (zero-based index).
     * 
     * @return The open-value.
     */
    public double getOpenValue(int series, int item) {
        double result = Double.NaN;
        Number open = getOpen(series, item);
        if (open != null) {
            result = open.doubleValue();   
        }
        return result;   
    }

    /**
     * Returns the close-value for the specified series and item.
     * <P>
     * Note:  throws <code>ClassCastException</code> if the series is not from a
     * {@link OHLCDataset}.
     *
     * @param series  the index of the series of interest (zero-based).
     * @param item  the index of the item of interest (zero-based).
     *
     * @return The close-value for the specified series and item.
     */
    public Number getClose(int series, int item) {
        DatasetInfo di = getDatasetInfo(series);
        return ((OHLCDataset) di.data).getClose(di.series, item);
    }

    /**
     * Returns the close-value (as a double primitive) for an item within a 
     * series.
     * 
     * @param series  the series (zero-based index).
     * @param item  the item (zero-based index).
     * 
     * @return The close-value.
     */
    public double getCloseValue(int series, int item) {
        double result = Double.NaN;
        Number close = getClose(series, item);
        if (close != null) {
            result = close.doubleValue();   
        }
        return result;   
    }

    /**
     * Returns the volume value for the specified series and item.
     * <P>
     * Note:  throws <code>ClassCastException</code> if the series is not from a
     * {@link OHLCDataset}.
     *
     * @param series  the index of the series of interest (zero-based).
     * @param item  the index of the item of interest (zero-based).
     *
     * @return The volume value for the specified series and item.
     */
    public Number getVolume(int series, int item) {
        DatasetInfo di = getDatasetInfo(series);
        return ((OHLCDataset) di.data).getVolume(di.series, item);
    }

    /**
     * Returns the volume-value (as a double primitive) for an item within a 
     * series.
     * 
     * @param series  the series (zero-based index).
     * @param item  the item (zero-based index).
     * 
     * @return The volume-value.
     */
    public double getVolumeValue(int series, int item) {
        double result = Double.NaN;
        Number volume = getVolume(series, item);
        if (volume != null) {
            result = volume.doubleValue();   
        }
        return result;   
    }

    ///////////////////////////////////////////////////////////////////////////
    // From IntervalXYDataset
    ///////////////////////////////////////////////////////////////////////////

    /**
     * Returns the starting X value for the specified series and item.
     *
     * @param series  the index of the series of interest (zero-based).
     * @param item  the index of the item of interest (zero-based).
     *
     * @return The value.
     */
    public Number getStartX(int series, int item) {
        DatasetInfo di = getDatasetInfo(series);
        if (di.data instanceof IntervalXYDataset) {
            return ((IntervalXYDataset) di.data).getStartX(di.series, item);
        }
        else {
            return getX(series, item);
        }
    }

    /**
     * Returns the ending X value for the specified series and item.
     *
     * @param series  the index of the series of interest (zero-based).
     * @param item  the index of the item of interest (zero-based).
     *
     * @return The value.
     */
    public Number getEndX(int series, int item) {
        DatasetInfo di = getDatasetInfo(series);
        if (di.data instanceof IntervalXYDataset) {
            return ((IntervalXYDataset) di.data).getEndX(di.series, item);
        }
        else {
            return getX(series, item);
        }
    }

    /**
     * Returns the starting Y value for the specified series and item.
     *
     * @param series  the index of the series of interest (zero-based).
     * @param item  the index of the item of interest (zero-based).
     *
     * @return The starting Y value for the specified series and item.
     */
    public Number getStartY(int series, int item) {
        DatasetInfo di = getDatasetInfo(series);
        if (di.data instanceof IntervalXYDataset) {
            return ((IntervalXYDataset) di.data).getStartY(di.series, item);
        }
        else {
            return getY(series, item);
        }
    }

    /**
     * Returns the ending Y value for the specified series and item.
     *
     * @param series  the index of the series of interest (zero-based).
     * @param item  the index of the item of interest (zero-based).
     *
     * @return The ending Y value for the specified series and item.
     */
    public Number getEndY(int series, int item) {
        DatasetInfo di = getDatasetInfo(series);
        if (di.data instanceof IntervalXYDataset) {
            return ((IntervalXYDataset) di.data).getEndY(di.series, item);
        }
        else {
            return getY(series, item);
        }
    }

    ///////////////////////////////////////////////////////////////////////////
    // New methods from CombinationDataset
    ///////////////////////////////////////////////////////////////////////////

    /**
     * Returns the parent Dataset of this combination. If there is more than
     * one parent, or a child is found that is not a CombinationDataset, then
     * returns <code>null</code>.
     *
     * @return The parent Dataset of this combination or <code>null</code>.
     */
    public SeriesDataset getParent() {

        SeriesDataset parent = null;
        for (int i = 0; i < this.datasetInfo.size(); i++) {
            SeriesDataset child = getDatasetInfo(i).data;
            if (child instanceof CombinationDataset) {
                SeriesDataset childParent 
                    = ((CombinationDataset) child).getParent();
                if (parent == null) {
                    parent = childParent;
                }
                else if (parent != childParent) {
                    return null;
                }
            }
            else {
                return null;
            }
        }
        return parent;

    }

    /**
     * Returns a map or indirect indexing form our series into parent's series.
     * Prior to calling this method, the client should check getParent() to make
     * sure the CombinationDataset uses the same parent. If not, the map
     * returned by this method will be invalid or null.
     *
     * @return A map or indirect indexing form our series into parent's series.
     *
     * @see #getParent()
     */
    public int[] getMap() {

        int[] map = null;
        for (int i = 0; i < this.datasetInfo.size(); i++) {
            SeriesDataset child = getDatasetInfo(i).data;
            if (child instanceof CombinationDataset) {
                int[] childMap = ((CombinationDataset) child).getMap();
                if (childMap == null) {
                    return null;
                }
                map = joinMap(map, childMap);
            }
            else {
                return null;
            }
        }
        return map;
    }

    ///////////////////////////////////////////////////////////////////////////
    // New Methods
    ///////////////////////////////////////////////////////////////////////////

    /**
     * Returns the child position.
     *
     * @param child  the child dataset.
     *
     * @return The position.
     */
    public int getChildPosition(Dataset child) {

        int n = 0;
        for (int i = 0; i < this.datasetInfo.size(); i++) {
            SeriesDataset childDataset = getDatasetInfo(i).data;
            if (childDataset instanceof CombinedDataset) {
                int m = ((CombinedDataset) childDataset)
                    .getChildPosition(child);
                if (m >= 0) {
                    return n + m;
                }
                n++;
            }
            else {
                if (child == childDataset) {
                    return n;
                }
                n++;
            }
        }
        return -1;
    }

    ///////////////////////////////////////////////////////////////////////////
    // Private
    ///////////////////////////////////////////////////////////////////////////

    /**
     * Returns the DatasetInfo object associated with the series.
     *
     * @param series  the index of the series.
     *
     * @return The DatasetInfo object associated with the series.
     */
    private DatasetInfo getDatasetInfo(int series) {
        return (DatasetInfo) this.datasetInfo.get(series);
    }

    /**
     * Joins two map arrays (int[]) together.
     *
     * @param a  the first array.
     * @param b  the second array.
     *
     * @return A copy of { a[], b[] }.
     */
    private int[] joinMap(int[] a, int[] b) {
        if (a == null) {
            return b;
        }
        if (b == null) {
            return a;
        }
        int[] result = new int[a.length + b.length];
        System.arraycopy(a, 0, result, 0, a.length);
        System.arraycopy(b, 0, result, a.length, b.length);
        return result;
    }

    /**
     * Private class to store as pairs (SeriesDataset, series) for all combined
     * series.
     */
    private class DatasetInfo {

        /** The dataset. */
        private SeriesDataset data;

        /** The series. */
        private int series;

        /**
         * Creates a new dataset info record.
         *
         * @param data  the dataset.
         * @param series  the series.
         */
        DatasetInfo(SeriesDataset data, int series) {
            this.data = data;
            this.series = series;
        }
    }

}