def missing_labels(self):
        """
        A 1D `~numpy.ndarray` of the sorted non-zero labels that are
        missing in the consecutive sequence from zero to the maximum
        label number.
        """

        return np.array(sorted(set(range(0, self.max_label + 1)).
                               difference(np.insert(self.labels, 0, 0))))
def missing_labels ( self ) : return np . array ( sorted ( set ( range ( 0 , self . max_label + 1 ) ) . difference ( np . insert ( self . labels , 0 , 0 ) ) ) )
A 1D `~numpy.ndarray` of the sorted non-zero labels that are
        missing in the consecutive sequence from zero to the maximum
        label number.