ROS学习 Python读写文本文件

我们在很多时候会需要保存一些文件以记录相关信息。

所以如何保存，我们第一个项目是想要保存rviz上点击的waypoints点。

代码如下：

import yaml
import rospy
import geometry_msgs.msg as geometry_msgs

class WaypointGenerator(object):

    def __init__(self, filename):
        self._sub_pose = rospy.Subscriber('clicked_point', geometry_msgs.PointStamped, self._process_pose, queue_size=1)
        self._waypoints = []
        self._filename = filename

    def _process_pose(self, msg):
        p = msg.point

        data = {}
        data['frame_id'] = msg.header.frame_id
        data['pose'] = {}
        data['pose']['position'] = {'x': p.x, 'y': p.y, 'z': 0.0}
        data['pose']['orientation'] = {'x': 0, 'y': 0, 'z': 0, 'w':1}
        data['name'] = '%s_%s' % (p.x, p.y)

        self._waypoints.append(data)
        rospy.loginfo("Clicked : (%s, %s, %s)" % (p.x, p.y, p.z))

    def _write_file(self):
        ways = {}
        ways['waypoints'] = self._waypoints
        with open(self._filename, 'w') as f:
            f.write(yaml.dump(ways, default_flow_style=False))

    def spin(self):
        rospy.spin()
        self._write_file()


if __name__ == '__main__':

    rospy.init_node('waypoint_generator')
    filename = rospy.get_param('~filename')

    g = WaypointGenerator(filename)
    rospy.loginfo('Initialized')
    g.spin()
    rospy.loginfo('ByeBye')

这个node就是订阅了rviz里面的Publish Point进行存储。

Make文件应该是这样的：

cmake_minimum_required(VERSION 2.8.3)
project(waypoint_generator)

find_package(catkin REQUIRED COMPONENTS
  geometry_msgs
  rospy
)

catkin_python_setup()
catkin_package()

install(PROGRAMS
  scripts/generator.py
  DESTINATION ${CATKIN_PACKAGE_BIN_DESTINATION}
)

我们在写一个launch文件，写好文件存储位置。

<launch>

<node pkg="waypoint_generator" type="generator.py" name="waypoint_generator" output="screen" >
  <param name="filename" value="$(find waypoint_generator)/output.txt" />
</node>
<node pkg="show_path" type="showpath" name="showpath"/>

</launch>

存储位置就是package下面主目录里。

下面是读取txt文件并且发布为goal，其中还包括了actionlib的用法。

import random
import rospy
import actionlib
import waypoint_touring.utils as utils

import move_base_msgs.msg as move_base_msgs
import visualization_msgs.msg as viz_msgs

class TourMachine(object):

    def __init__(self, filename, random_visits=False, repeat=False):
        self._waypoints = utils.get_waypoints(filename)

        action_name = 'move_base'
        self._ac_move_base = actionlib.SimpleActionClient(action_name, move_base_msgs.MoveBaseAction)
        rospy.loginfo('Wait for %s server' % action_name)
        self._ac_move_base.wait_for_server
        self._counter = 0
        self._repeat = repeat
        self._random_visits = random_visits

        if self._random_visits:
            random.shuffle(self._waypoints)
        self._pub_viz_marker = rospy.Publisher('viz_waypoints', viz_msgs.MarkerArray, queue_size=1, latch=True)
        self._viz_markers = utils.create_viz_markers(self._waypoints)

    def move_to_next(self):
        p = self._get_next_destination()

        if not p:
            rospy.loginfo("Finishing Tour")
            return True

        goal = utils.create_move_base_goal(p)
        rospy.loginfo("Move to %s" % p['name'])
        self._ac_move_base.send_goal(goal)
        self._ac_move_base.wait_for_result()
        result = self._ac_move_base.get_result()
        rospy.loginfo("Result : %s" % result)

        return False

    def _get_next_destination(self):
        if self._counter == len(self._waypoints):
            if self._repeat:
                self._counter = 0
                if self._random_visits:
                    random.shuffle(self._waypoints)
            else:
                next_destination = None
        next_destination = self._waypoints[self._counter]
        self._counter = self._counter + 1
        return next_destination

    def spin(self):
        rospy.sleep(1.0)
        self._pub_viz_marker.publish(self._viz_markers)
        finished = False
        while not rospy.is_shutdown() and not finished:
            finished = self.move_to_next()
            rospy.sleep(2.0)

if __name__ == '__main__':
    rospy.init_node('tour')

    filename = rospy.get_param('~filename')
    random_visits = rospy.get_param('~random', False)
    repeat = rospy.get_param('~repeat', False)

    m = TourMachine(filename, random_visits, repeat)
    rospy.loginfo('Initialized')
    m.spin()
    rospy.loginfo('Bye Bye')

而写一个launch文件来读取txt位置，

<launch>
    <arg name="repeat"        default="true"/>
    <arg name="random"        default="false"/>
    <arg name="filename"    default="$(find waypoint_generator)/output.txt"/>

    <node pkg="rviz" type="rviz" name="rviz" />

    <node pkg="waypoint_touring" name="waypoint_touring" type="tour.py" output="screen">
      <param name="filename"    value="$(arg filename)"/>
      <param name="repeat"        value="$(arg repeat)"/>
      <param name="random"        value="$(arg random)"/>
    </node>
</launch>

参考资料：

https://github.com/jihoonl/waypoint