Creating and running publisher and subscriber nodes

If you have understood how the requirement, distance-sensor.py, publisher script works, then the following subscriber script should be pretty straightforward to follow:

#!/usr/bin/env python

import rospy
from sensor_msgs.msg import Range

def callback(msg):
    print msg.data
    rospy.loginfo(rospy.get_caller_id() + 'GoPiGo3 measures distance %s mm', msg.data*1000)

rospy.init_node('distance_sensor_subscriber')

sub = rospy.Subscriber('distance_sensor/distance', Range, callback)

rospy.spin()

This snippet corresponds to the distance-sensor_subscriber.py file in the ./pkg_mygopigo/src folder of the code for this chapter. The main difference in the subscriber script is that, since we are listening to a topic, we do not need to specify a rate of execution. We simply loop forever with the following line:

rospy...