text: #! /usr/bin/env python
  
  import rospy
  from sensor_msgs.msg import LaserScan
  
  def callback(msg):
      print 'length: %s' % (len(msg.ranges))
  	# values at 0 degree
      print msg.ranges[0]
      # values at 90 degree
      print msg.ranges[90]
      # values at 180 degree
      print msg.ranges[234]
      
      print msg.angle_min
      print msg.angle_max
  rospy.init_node('scan_values')
  sub = rospy.Subscriber('/m2wr/laser/scan', LaserScan, callback)
  rospy.spin()
  