http://wiki.ros.org/rospy/Overview/Parameter%20Server

rospy.get_param(param_name)

   1 global_name = rospy.get_param("/global_name")
   2 relative_name = rospy.get_param("relative_name")
   3 private_param = rospy.get_param('~private_name')
   4 default_param = rospy.get_param('default_param', 'default_value
 
')
   5 
   6 # fetch a group (dictionary) of parameters
   7 gains = rospy.get_param('gains')
   8 p, i, d = gains['p'], gains['i'], gains['d']

rospy.set_param(param_name,param_value)

  1 # Using rospy and raw python objects
   2 rospy.set_param('a_string', 'baz')
   3 rospy.set_param('~private_int
 
', 2)
   4 rospy.set_param('list_of_floats', [1., 2., 3., 4.])
   5 rospy.set_param('bool_True', True)
   6 rospy.set_param('gains', {'p': 1, 'i': 2, 'd': 3})
   7 
   8 # Using rosparam and yaml strings
   9 rosparam.set_param('a_string', 'baz')
  10 rosparam.set_param('~private_int', '2')
  11 rosparam.set_param('
 
list_of_floats', "[1., 2., 3., 4.]")
  12 rosparam.set_param('bool_True', "true")
  13 rosparam.set_param('gains', "{'p': 1, 'i': 2, 'd': 3}")
  14 
  15 rospy.get_param('gains/p') #should return 1

rospy.has_param(param_name)

 1 if rospy.has_param('to_delete'):
   2     rospy.delete_param('to_delete')

rospy.delete_param(param_name)

  1 try:
   2     rospy.delete_param('to_delete')
   3 except KeyError:
   4     print("value not set")