// This method will be called when a radio button is selected.
// If the selected series is different from the model's last
// singly selected series number, store it in the model.
public void actionPerformed(ActionEvent e) {
String seriesName = e.getActionCommand();
SeriesType selectedSeries = SeriesType
.getSeriesFromDescription(seriesName);
if (selectedSeries != obsPlotModel.getLastSinglySelectedSeries()) {
obsPlotModel.setLastSinglySelectedSeries(selectedSeries);
}