def __mul__(self, repeat): result = Graph.__mul__(self, repeat) result.__class__ = MolecularGraph # copy numbers numbers = numpy.zeros((repeat, len(self.numbers)), int) numbers[:] = self.numbers result._numbers = numbers.ravel() result._numbers.setflags(write=False) # copy orders orders = numpy.zeros((repeat, len(self.orders)), int) orders[:] = self.orders result._orders = orders.ravel() result._orders.setflags(write=False) return result