编写一段python代码订阅里程计信息转换成路径显示到导入的地图上，输出png

import rospy
from nav_msgs.msg import Odometry
import matplotlib.pyplot as pltdef callback(odom):
x, y = odom.pose.pose.position.x, odom.pose.pose.position.y
plt.plot(x, y, 'ro')rospy.init_node('route_map')
sub = rospy.Subscriber('/odom', Odometry, callback) #订阅里程计信息# 导入地图
map_data = ... # 将里程计信息转换成路径并显示到地图上
...# 输出png
plt.imshow(map_data)
plt.savefig('route_map.png')