def  plot_item(self, m, ind, x, r, k, label, U, rerr, feature_weights):
    """plot_item(self, m, ind, x, r, k, label, U, rerr, feature_weights)

    Plot selection m (index ind, data in x) and its reconstruction r,
    with k and label to annotate of the plot.
    Use fancy ChemCam elemental annotations.

    If feature_weights are specified, omit any 0-weighted features from the plot.
    """

    if x == [] or r == []: 
      print "Error: No data in x and/or r."
      return