An error for publishing nav_msgs/Odometry [closed]

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In a simulator, I am trying to write a python script which subscribe a nav_msgs/Odometry topic to add a frame between odom and base_footprint. It then also publishes another nav_msgs/Odometry topic under frame odom. The callback function for the subscriber is here:

#!/usr/bin/env python
import roslib
roslib.load_manifest('simulator')
import rospy, tf
from geometry_msgs.msg import Point, Quaternion, PoseStamped
from nav_msgs.msg import Odometry
import xml.dom.minidom

def newDataAvailable(robotPose):
    robotPosition=float(robotPose.pose.pose.position.x) -x, float(robotPose.pose.pose.position.y) -y,0.0
    robotOrientation=robotPose.pose.pose.orientation.x, robotPose.pose.pose.orientation.y, robotPose.pose.pose.orientation.z, robotPose.pose.pose.orientation.w
    robotVelocity=(robotPose.twist.twist.linear.x,robotPose.twist.twist.linear.y,robotPose.twist.twist.linear.z)
    currentTime = rospy.Time.now()
    br.sendTransform(robotPosition, robotOrientation, currentTime, "base_footprint", "odom")

    odom = Odometry()
    odom.header.stamp = rospy.Time.now()
    odom.header.frame_id = parentFrameId
    odom.child_frame_id = frameId
    odom.pose.pose.position = robotPosition
    print odom.pose.pose.position
    odom.pose.pose.orientation = robotOrientation
    print "print orientation"
    print odom.pose.pose.orientation
    odom.twist.twist.linear=Point(*robotVelocity)
    print odom.twist
    odomPublisher.publish(odom)



def main():
    rospy.init_node('simulator_robot_tf_broadcaster')
    global frameId, parentFrameId, br, x, y, odomPublisher
    frameId = rospy.get_param("frame", "base_footprint")
    parentFrameId = rospy.get_param("parent_frame", "odom")
    robotgroundtruthTopic = "/robot_pose"
    rospy.Subscriber(robotgroundtruthTopic, Odometry, newDataAvailable)
    odomPublisher=rospy.Publisher("/base_pose_ground_truth", Odometry, 10)

    scene_file_param=rospy.get_param("/scene_file",  "scene.xml")
    dom = xml.dom.minidom.parse(scene_file_param)
    root = dom.documentElement
    itemlist = dom.getElementsByTagName('agent')
    for i in itemlist:
        pn = i.getAttribute("type")
        if pn=="2":           # robot:2 
           print "I got the robot's initial postion"
           x = i.getAttribute("x")
           #print x
           y = i.getAttribute("y")
           #print y

    br = tf.TransformBroadcaster()
    x=float(x)
    y=float(y)    
    print x,y
    rospy.spin()


if __name__ == '__main__':
    main()

When I run it, an error comes out:

File "/opt/ros/hydro/lib/python2.7/dist-packages/nav_msgs/msg/_Odometry.py", line 161, in serialize
    buff.write(_struct_7d.pack(_x.pose.pose.position.x, _x.pose.pose.position.y, _x.pose.pose.position.z, _x.pose.pose.orientation.x, _x.pose.pose.orientation.y, _x.pose.pose.orientation.z, _x.pose.pose.orientation.w))
AttributeError: 'tuple' object has no attribute 'x'

All print functions work fine. However, no message outputs from topic "/base_pose_ground_truth"

EDIT1: I modified some places of code as:

   robotPosition=robotPose.pose.pose.position.x - x, robotPose.pose.pose.position.y-y, 0.0
    robotOrientation=(robotPose.pose.pose.orientation.x, robotPose.pose.pose.orientation.y, robotPose.pose.pose.orientation.z, robotPose.pose.pose.orientation.w)
    robotVelocity=(robotPose.twist.twist.linear.x,robotPose.twist.twist.linear.y,robotPose.twist.twist.linear.z)
    currentTime = rospy.Time.now()
    br.sendTransform(robotPosition, robotOrientation, currentTime, "base_footprint", "odom")
    odom = Odometry()
    odom.header.stamp = rospy.Time.now()
    odom.header.frame_id = parentFrameId
    odom.child_frame_id = frameId
    odom.pose.pose.position = Point(*robotPosition)
    odom.pose.pose.orientation =Quaternion(*robotOrientation)
    odom.twist.twist.linear=Point(*robotVelocity)
    odomPublisher.publish(odom)

Then above error(simplified) disappears. Message output from topic "/base_pose_ground_truth" also but in a lower speed comparing ... (more)