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Retrieve list of lists from yaml file / parameter server

asked 2019-03-14 11:35:22 -0500

strike_eagle_iii gravatar image

updated 2019-03-14 11:46:57 -0500

I have a yaml file with a list of 3D points:

bb1:   corners: [[-0.009000421,
-32.9505, 3.071861], [-0.009000659, -34.8755, 3.071861], [-0.009000659, -34.8755, 1.134362], [-0.009000421, -32.9505, 1.134362]]   bound: [2.5, 2.5, 5.0]

I've got it in the launch file and can can successfully test for the param:

 if(n.hasParam("path/bb1/corners"))

however I can't figure out how to actually read the values. I've looked here: http://wiki.ros.org/roscpp/Overview/P...

however the most it gives an example is how to retrieve a list of primitive types.

I tried XmlRpc::XmlRpcValue as well but if I

    XmlRpc::XmlRpcValue cornerlist;
    n.getParam("path/bb1/corners", cornerlist);
    std::cout << "corner type: " << cornerlist.getType() << std::endl;

actually appears to work (was previously getting an error here, but had a typo in the param name). Is that the best way? How do I get the list of lists?

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answered 2019-03-14 12:50:40 -0500

ahendrix gravatar image

Yep, you're on the right track. I had to do this for one of my projects a while back ( https://github.com/trainman419/dagny_... ):

 // load goal list from parameter server
 XmlRpc::XmlRpcValue xml_goals;
 n.getParam("goals", xml_goals);
 if( xml_goals.getType() != XmlRpc::XmlRpcValue::TypeArray ) {
    ROS_ERROR("param 'goals' is not a list");
 } else {
    for( int i=0; i<xml_goals.size(); ++i ) {
       if( xml_goals[i].getType() != XmlRpc::XmlRpcValue::TypeArray ) {
          ROS_ERROR("goals[%d] is not a list", i);
       } else {
          if( xml_goals[i].size() != 2 ) {
             ROS_ERROR("goals[%d] is not a pair", i);
          } else if( 
           xml_goals[i][0].getType() != XmlRpc::XmlRpcValue::TypeDouble ||
           xml_goals[i][1].getType() != XmlRpc::XmlRpcValue::TypeDouble ) {
             ROS_ERROR("goals[%d] is not a pair of doubles", i);
          } else {
             double a = xml_goals[i][0];
             double b = xml_goals[i][1];
          }
       }
    }
 }
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Asked: 2019-03-14 11:35:22 -0500

Seen: 1,062 times

Last updated: Mar 14 '19