How to subscribe to odom properly in python

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Hello, all,

I recently wrote a simple subscriber that subscribes to the topic /odom coming from the irobot_create_2_1 driver for an iCreate. However, when I simply print the odometry data and rotate the wheels myself, the data doesn't change. At the same time, though, if I re-run the Python Script, the data will have changed to the amount I previously rotated it.

Have I made a simple mistake? Or does /odom not publish the current transformation and rotation information.

(I noticed also that the time stamp doesn't change)

Thanks so much in advance for any advice!

Here's my source code:

#!/usr/bin/env python
import roslib; roslib.load_manifest('Phoebe')
import rospy
import irobot_create_2_1

from nav_msgs.msg import Odometry
from geometry_msgs.msg import *
from tf.msg import *



counter = 0

def Position(odom_data):

    global counter
    rospy.sleep(1)
    curr_time = odom_data.header.stamp
    pose = odom_data.pose.pose #  the x,y,z pose and quaternion orientation
    counter= counter+1
    print counter, curr_time
    print
    print pose


def transformation(tf_data):
    global counter
    rospy.sleep(1)
    transform = tf_data.transform
    print transform


def begin():
    while not rospy.is_shutdown():
        rospy.init_node('oodometry', anonymous=True) #make node 
        rospy.Subscriber('odom',Odometry,Position)


if __name__ == "__main__":
    begin()
    rospy.spin() # not really necessary because we have while not rospy.is_shutdown()