ros2-msg-transformations

Transform ROS2 messages to Python structures.

Methods

Convert ROS2 structures to OrderedDict

Can be used to transform any type of ROS2 communication message (Topic Message, Service Message, Action Message) to an OrderedDict

def ros2_msg_to_dict(msg: Any) -> OrderedDict:
    """ros2_msg_to_dict.
    Converts a ROS2 communication message to an OrderedDict.

    Args:
        msg: ROS2 Message to transform. Can be one of type:
            - Topic Message (Message)
            - Service Request Message (Service.Request)
            - Service Response Message (Service.Response)
            - Action Goal Message (Action.Goal)
            - Action Cancel Message (Action.Cancel)
            - Action Result Message (Action.Result)
            - Action Status Message (Action.Status)
            - Action Feedback Message (Action.Feedback)
    """

Below are two examples, one for converting a ROS2 msg and one for converting a ROS2 srv into an OrderedDict.

from sensor_msgs.msg import Range

msg = Range()
_dict = ros2_msg_to_dict(msg)

from std_srvs.srv import SetBool

req = SetBool.Request()
_dict = ros2_msg_to_dict(req)

Convert an OrderedDict to a ROS2 communication structure

Can be used to transform into any type of ROS2 communication message (Topic Message, Service Message, Action Message).

def dict_to_ros2_msg(py_dict: OrderedDict, msg_cls: Any) -> Any:
    """dict_to_ros2_msg.
    Converts a dict/OrderedDict into a ROS2 message, given the message cls
        as input.

    Args:
        py_dict (OrderedDict): Dict/OrderedDict to convert to ROS2 message.
        msg_cls (Any): ROS2 Message class.
            - Topic Message (Message)
            - Service Request Message (Service.Request)
            - Service Response Message (Service.Response)
            - Action Goal Message (Action.Goal)
            - Action Cancel Message (Action.Cancel)
            - Action Result Message (Action.Result)
            - Action Status Message (Action.Status)
            - Action Feedback Message (Action.Feedback)
    """

Below are two examples, one for converting a ROS2 msg and one for converting a ROS2 srv into an OrderedDict.

from sensor_msgs.msg import Range

_dict = {
    'range': 10.0,
    'min_range': 0.2,
    'max_range': 240.0,
    'field_of_view': 60.0,
    'radiation_type': 0,
}
_msg = dict_to_ros2_msg(_dict, Range)

from std_srvs.srv import SetBool

...

_req = dict_to_ros2_msg(_dict, SetBool.Request)
_resp = dict_to_ros2_msg(_dict, SetBool.Response)

You can also construct from and to ROS2 message structures without the need to import them. This is achieved via passing a string that includes the namespace of the message.

_msg = dict_to_ros2_msg_from_ns(_dict, 'sensor_msgs/Range')

_msg = dict_to_ros2_srv_from_ns(_dict, 'std_srvs/SetBool.Request')