Hands-On ROS for Robotics Programming

Including the required libraries – rospy and msgs.msg

The following two lines import the required ROS libraries:

import rospyfrom sensor_msgs.msg import Range

These libraries are explained as follows:

• rospy (http://wiki.ros.org/rospy): This is the official Python client for ROS. It implements API methods so that you can integrate ROS nodes coded in Python.
• sensor_msgs (http://wiki.ros.org/sensor_msgs): This is the ROS package that lets you handle different types of ROS message depending on the sensors and drives of your robot; for example, BatteryState, FluidPressure, and LaserScan. In the case of the distance sensor, we use the Range type.