ROS知识点（2）_从bag文件中读取相应的topic数据

void readDataFromBag(const std::string &bag_name, const std::string &amcl_topic_name, const std::string &wheel_topic_name）
{
  rosbag::Bag bag;
  try
  {
    bag.open(bag_name, rosbag::bagmode::Read);
  }
  catch (std::exception& e) 
  {
    std::cout << "ERROR!" << std::endl;
    exit(-1);
  }
  std::vector<std::string> topics;
  topics.push_back(wheel_topic_name);
  topics.push_back(amcl_topic_name);
  std::cout<<topics.at(0)<<topics.at(1)<<std::endl;

  rosbag::View view(bag, rosbag::TopicQuery(topics.at(0)));//读取nav_msgs::odometry格式的轮式里程计数据
  for (rosbag::MessageInstance const m: view) 
  {
    nav_msgs::OdometryConstPtr odom_wheel=m.instantiate<nav_msgs::Odometry>();
    if(odom_wheel!=NULL)
    {
		......
    }  
  }

  rosbag::View view1(bag, rosbag::TopicQuery(topics.at(1)));//读取nav_msgs::odometry格式的amcl里程计数据
  {
    for(rosbag::MessageInstance const m:view1)
    {
      nav_msgs::OdometryConstPtr odom_amcl=m.instantiate<nav_msgs::Odometry>();
      if(odom_amcl!=NULL)
      {
      	.....
      }
    }
  }
  bag.close();
  return;
}
int main(int argc,char **argv)
{
    ros::init(argc,argv,"data_analyse");
    ros::NodeHandle nh("~");
    std::string file_path;
    std::string bagname;
    std::string odom_wheel_topic;
    std::string odom_amcl_topic;
	ros::param::get("~file_path", file_path);
	ros::param::get("~bagname", bagname);
	ros::param::get("~odom_wheel_topic", odom_wheel_topic);
	ros::param::get("~odom_amcl_topic", odom_amcl_topic);
	readDataFromBag(bagfile,odom_amcl_topic,odom_wheel_topic);
	std::string bagfile=file_path+bagname+".bag";
	ros::spin();
    return 0;

以上简单地写了个从bag文件中读取两个topic的软件框架，如果有多个topic要读，最好把rosbag viewer写成vector容器遍历的形式。

 rosbag::View view(bag, rosbag::TopicQuery(topics);
 foreach(rosbag::MessageInstance const m:view)
 {
	nav_msgs::OdometryConstPtr odom_wheel=m.instantiate<nav_msgs::Odometry>();
	if(odom_wheel!=NULL)
	{
		......
	}  
	nav_msgs::OdometryConstPtr odom_amcl=m.instantiate<nav_msgs::Odometry>();
	if(odom_amcl!=NULL)
	{
		.....
	}
}