code: private String[] convertIndsToLabels(int... ind)
  	{
  		String[] label = new String[ind.length];
  		for (int i = 0; i < ind.length; i++)
  		{
  			if (!hasLabel(ind[i])) throw new IllegalArgumentException(
  				"The index " + ind[i] + " does not have a label.");
  
  			label[i] = getLabel(ind[i]);
  		}
  		return label;
  	}
docs: Converts the indices to the labels. All indices must have an existing label.
  @param ind indices
  @return labels for indices