ROS2 example on how to parse complex yaml files to be used as parameters for a Node based on python.
This using this package depends on pyyaml and anytree . You can easily install them both using the following command:
pip install pyyaml
pip install anytreeThe code parses the contents of the yaml file as a dictionary.
Alert: ros__parameters: for the code to work.
The first item in the yaml file is parsed as an object, not as a dictionary by default when using the anytree importer. I solved it by forcing the user to use ros__parameters: as the first variable and then ignoring it.
import os
from ament_index_python.packages import get_package_share_directory
from launch.actions import DeclareLaunchArgument
from launch.substitutions import LaunchConfiguration
DeclareLaunchArgument(name = "parameters_file_path",
description ="--params-file (name of the spot to identify)",
default_value = os.path.join(get_package_share_directory('ros2_yaml_parser'), 'config', 'spots.yaml')),
arguments=[
'--params-file', LaunchConfiguration("parameters_file_path"),
'--spot', LaunchConfiguration("spot_to_find")],import argparse
import os
from ament_index_python.packages import get_package_share_directory
from anytree.importer import DictImporter
import yaml
# PARSE ARGUMENTS
parser = argparse.ArgumentParser()
parser.add_argument('--params-file', type=str, default=os.path.join(get_package_share_directory('ros2_yaml_parser'), 'config', 'spots.yaml'), help='Size argument')
args, _ = parser.parse_known_args()
parsed_dictionary = yaml_to_dictionary(args.params_file)
def yaml_to_dictionary(file_path):
with open(file_path, 'r') as yaml_file:
yaml_data = yaml.safe_load(yaml_file)
parsed_data = DictImporter().import_(yaml_data)
return parsed_data.ros__parametersYou can easily download this package and test it by downloading it into your src
You can easily test the package using the following command to execute the launchfile:
ros2 launch ros2_yaml_parser yaml_test.launch.pyOr check the code for other spots by using another spot label as an input argument:
ros2 launch ros2_yaml_parser yaml_test.launch.py spot:="corner2"
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