ROS2 Topic name rename and namespace

remap

ros2 run package node --ros-args -r old_topic:=new_topic

Demo

• Two nodes
• pub publish string message in pub_topic
• sub subscribe to string message in sub_topic

pub sub code

#!/usr/bin/env python3


import rclpy
from rclpy.node import Node
from std_msgs.msg import String

TOPIC = "pub_topic"

class PubNode(Node):
    def __init__(self):
        node_name="pub"
        super().__init__(node_name)
        self.pub = self.create_publisher(String, TOPIC,10)
        self.timer = self.create_timer(1.0, self.timer_handler)
        self.get_logger().info("Hello PUB")

    def timer_handler(self):
        msg = String()
        msg.data = "hello"
        self.pub.publish(msg)

def main(args=None):
    rclpy.init(args=args)
    node = PubNode()
    rclpy.spin(node)
    node.destroy_node()
    rclpy.shutdown()

if __name__ == '__main__':
    main()

#!/usr/bin/env python3


import rclpy
from rclpy.node import Node
from std_msgs.msg import String

TOPIC = "sub_topic"

class SubNode(Node):
    def __init__(self):
        node_name="pub"
        super().__init__(node_name)
        self.pub = self.create_subscription(String, TOPIC, self.callback, 10)
        self.get_logger().info("Hello SUB")

    def callback(self, msg):
        self.get_logger().info(msg.data)

def main(args=None):
    rclpy.init(args=args)
    node = SubNode()
    rclpy.spin(node)
    node.destroy_node()
    rclpy.shutdown()

if __name__ == '__main__':
    main()

usage

• remap subscriber node

ros2 run g_stream pub.py

ros2 run g_stream sub.py --ros-args -r sub_topic:=pub_topic

• remap pub node

ros2 run g_stream pub.py --ros-args -r pub_topic:=sub_topic

ros2 run g_stream sub.py 

---

Namespace

change from CLI

ros2 run g_stream pub.py --ros-args -r __ns:=/ns1

ros2 topic list
#
/ns1/pub_topic