ROS publisher from launch file

publishers_from_launch_ file.txt

ROS Marker publisher:  

Step 1: Transform Yaml file into Python dict notation.

Alternative 1, online tool:
A useful tool which will shows the result in Python notation of any YAML input is:  
https://yaml-online-parser.appspot.com/  
Make sure to remove excess single quotes (') and new lines.  

Alternative 2, use a python :
# if needed install pyyaml 
import yaml

with open('filename.yaml') as f:
    loadad_yaml = yaml.safe_load(f)

Then loadad_yaml returns a python dictionary.

Step 2, add publisher to launch file:  

<!-- publish a marker with rostopic (CUBE, type:1; SPHERE, type:2; CYLINDER, type:3) -->
<node name="pub1" pkg="rostopic" type="rostopic" args="pub /shape visualization_msgs/Marker '{header: {frame_id: 'map', seq: 0, stamp: {nsecs: 0, secs: 0}}, ns: 'MarkerWithShape', id: 0, type: 1, action: 0, pose: {orientation: {w: 1.0, x: 0.0, y: 0.0, z: 0.0}, position: {x: 0.0, y: 0.0, z: 0.0}},scale: {x: 2.0, y: 2.0, z: 2.0}, color: {a: 1.0, b: 0.0, g: 0.0, r: 1.0}, lifetime: {nsecs: 0, secs: 0},frame_locked: False, points: [{x: 0.0, y: 0.0, z: 0.0}], colors: [{a: 1.0, b: 0.0, g: 0.0, r: 1.0}], text: '',mesh_resource: '', mesh_use_embedded_materials: False}'"/>


or

<!-- publish a marker with rostopic (CUBE, type:1; SPHERE, type:2; CYLINDER, type:3) -->
<arg name="start" value="'{header: {frame_id: 'map', seq: 0, stamp: {nsecs: 0, secs: 0}}, ns: 'MarkerWithShape', id: 0, type: 1, action: 0, pose: {orientation: {w: 1.0, x: 0.0, y: 0.0, z: 0.0}, position: {x: -1.9, y: 5.1, z: 0.0}},scale: {x: 0.2, y: 0.2, z: 0.1}, color: {a: 1.0, b: 0.0, g: 0.0, r: 1.0}, lifetime: {nsecs: 0, secs: 0},frame_locked: False, points: [{x: 0.0, y: 0.0, z: 0.0}], colors: [{a: 1.0, b: 0.0, g: 0.0, r: 1.0}], text: '',mesh_resource: '', mesh_use_embedded_materials: False}'" />

<node name="pub1" pkg="rostopic" type="rostopic" args="pub /shape visualization_msgs/Marker $(arg start)"/>


Multiple marker publishers using nested substitution args:  <arg> $(arg) 

  <arg name="header" value="header: {frame_id: 'map', seq: 0, stamp: {nsecs: 0, secs: 0}}" />
  <arg name="start_conc" value="'{$(arg header), ns: 'MarkerWithShape', id: 0, type: 1, action: 0, pose: {orientation: {w: 1.0, x: 0.0, y: 0.0, z: 0.0}, position: {x: -1.9, y: 5.1, z: 0.1}},scale: {x: 0.2, y: 0.2, z: 0.2}, color: {a: 1.0, b: 1.0, g: 0.0, r: 0.0}, lifetime: {nsecs: 0, secs: 0},frame_locked: False, points: [{x: 0.0, y: 0.0, z: 0.0}], colors: [{a: 1.0, b: 0.0, g: 0.0, r: 1.0}], text: '',mesh_resource: '', mesh_use_embedded_materials: False}'" />
  <arg name="end_conc" value="'{$(arg header), ns: 'MarkerWithShape', id: 1, type: 1, action: 0, pose: {orientation: {w: 1.0, x: 0.0, y: 0.0, z: 0.0}, position: {x: 3.7, y: 0.3, z: 0.1}},scale: {x: 0.2, y: 0.2, z: 0.2}, color: {a: 1.0, b: 0.0, g: 0.0, r: 1.0}, lifetime: {nsecs: 0, secs: 0},frame_locked: False, points: [{x: 0.0, y: 0.0, z: 0.0}], colors: [{a: 1.0, b: 0.0, g: 0.0, r: 1.0}], text: '',mesh_resource: '', mesh_use_embedded_materials: False}'" />
  <node name="pub1" pkg="rostopic" type="rostopic" args="pub /shape visualization_msgs/Marker $(arg start_conc)"/>
  <node name="pub2" pkg="rostopic" type="rostopic" args="pub /shape visualization_msgs/Marker $(arg end_conc)"/>