ROS执行python文件遇到错误ModuleNotFoundError: No module named ‘yaml‘解决方法

       实现订阅者Subscriber的测试编程，执行命令：

$ rosrun learning_topic pose_subscriber.py

        遇到如下错误：

Traceback (most recent call last):
  File "/home/yue/catkin_ws/src/learning_topic/scripts/pose_subscriber.py", line 10, in 
    import rospy
  File "/opt/ros/melodic/lib/python2.7/dist-packages/rospy/__init__.py", line 47, in 
    from std_msgs.msg import Header
  File "/opt/ros/melodic/lib/python2.7/dist-packages/std_msgs/msg/__init__.py", line 1, in 
    from ._Bool import *
  File "/opt/ros/melodic/lib/python2.7/dist-packages/std_msgs/msg/_Bool.py", line 6, in 
    import genpy
  File "/opt/ros/melodic/lib/python2.7/dist-packages/genpy/__init__.py", line 34, in 
    from . message import Message, SerializationError, DeserializationError, MessageException, struct_I
  File "/opt/ros/melodic/lib/python2.7/dist-packages/genpy/message.py", line 48, in 
    import yaml
ModuleNotFoundError: No module named 'yaml'

解决方法：

        $ rosrun learning_topic pose_subscriber.py ；

        在上述命令行的基础上删除.py后缀，就可以了。

实验结果：删除.py后缀，可以看出程序执行正常。

$ rosrun learning_topic pose_subscriber