显示 ROS 消息的子字段

Question

对于给定的 ros 消息，有什么方法可以获取 ros-message 的子字段。我正在使用 python 脚本从 rosbag 文件中读取消息，

"for topic, msg, t in bag.read_messages(): "

现在给定主题和消息，我可以显示消息的子字段吗？

例如： nav/Odometry.msg 具有子字段：“header”、“child_frame_id”、“pose”和“twist”。 (Reference link)

是否有将子字段作为输出返回的命令？ .. 如果我事先不知道子字段

谢谢

Answer 1

这是一个简单的 python 节点（基于this），它完全符合您的要求：

#!/usr/bin/env python
import rospy
from nav_msgs.msg import Odometry 

def callback(data):
    rospy.loginfo(rospy.get_caller_id() + "I heard %s", data.header)
    rospy.loginfo(rospy.get_caller_id() + "child_frame_id %s", data.child_frame_id)
    rospy.loginfo(rospy.get_caller_id() + "pose %s", data.pose)
    rospy.loginfo(rospy.get_caller_id() + "twist %s", data.twist)

def listener():

    # In ROS, nodes are uniquely named. If two nodes with the same
    # node are launched, the previous one is kicked off. The
    # anonymous=True flag means that rospy will choose a unique
    # name for our 'listener' node so that multiple listeners can
    # run simultaneously.
    rospy.init_node('listener', anonymous=True)

    rospy.Subscriber("odom_topic", Odometry, callback)

    # spin() simply keeps python from exiting until this node is stopped
    rospy.spin()

if __name__ == '__main__':
    listener()