if (this.data.size() > 0) {
            for (int index = start; index <= end; index++) {
                XYDataItem item = (XYDataItem) this.data.get(index);
                XYDataItem clone = (XYDataItem) item.clone();
                try {
                    copy.add(clone);
                }
                catch (SeriesException e) {
                    System.err.println("Unable to add cloned data item.");