def METHOD_NAME(self):
    if self.n:
        i = self.property_id.argsort()
        self.property_id = self.property_id[i]
        self.material_id = self.material_id[i]
        self.stress_strain = self.stress_strain[i]
        unique_pids = unique(self.property_id)
        if len(unique_pids) != len(self.property_id):
            raise RuntimeError('There are duplicate PLSOLID IDs...')
    else:
        self.property_id = array([], dtype='int32')
        self.material_id = array([], dtype='int32')