add data to the graph

def add_mavlink_packet(self, msg):
        '''add data to the graph'''
        mtype = msg.get_type()
        if mtype not in self.msg_types:
            return
        for i in range(len(self.fields)):
            if mtype not in self.field_types[i]:
                continue
            f = self.fields[i]
            self.values[i] = mavutil.evaluate_expression(f, self.state.master.messages)
        if self.livegraph is not None:
            self.livegraph.add_values(self.values)