realtime_factor.py

#!/usr/bin/env python

# A simple script to print the realtime factor under simulated time.
import time
import rospy

from rosgraph_msgs.msg import Clock

last_wall_time = time.time()
last_clock_time = rospy.Time(0)

def callback(data):
    global last_wall_time
    global last_clock_time
    current_wall = time.time()
    wall_elapsed = current_wall - last_wall_time
    clock_elapsed = data.clock - last_clock_time
    if wall_elapsed < 1.0:
        return
    realtime_factor = clock_elapsed.to_sec()/wall_elapsed
    rospy.loginfo("Realtime Factor: %s" % (realtime_factor))
    last_wall_time = current_wall
    last_clock_time = data.clock

rospy.init_node('realtime_factor', anonymous=True)
rospy.Subscriber('/clock', Clock, callback)
rospy.spin()