python ros topic demo

发布者：

#!/usr/bin/env python
#coding=utf-

import rospy
from std_msgs.msg import String

def talker():
    pub = rospy.Publisher('chatter',String, queue_size=)
    rospy.init_node('talker',anonymous=True)
    rate = rospy.Rate() # 10hz
    while not rospy.is_shutdown():
        hello_str = "超哥 好帅啊 %s" % rospy.get_time()
        rospy.loginfo(hello_str)
        pub.publish(hello_str)
        rate.sleep()

if __name__ == '__main__':
    try:
        talker()
    except rospy.ROSInterruptException:
        pass

---

• from std_msgs.msg import String

• 分析：

• 导入python的标准字符处理库
• String是一个函数，可以另外方式赋值

msg = String()
msg.data = str

或

String(data=str)

---

订阅者：

#!/usr/bin/env python
#coding=utf-

import rospy
from std_msgs.msg import String

def callback(data):
    rospy.loginfo(rospy.get_caller_id() + '我觉得 %s', data.data)

def listener():

    # In ROS, nodes are uniquely named. If two nodes with the same
    # name are launched, the previous one is kicked off. The
    # anonymous=True flag means that rospy will choose a unique
    # name for our 'listener' node so that multiple listeners can
    # run simultaneously.
#对上面注释翻译
    ＃在ROS中，节点是唯一命名的。 如果两个节点相同
    ＃名称被启动，前一个被启动。该
    ＃anonymous = True标志意味着rospy会选择一个独特的
    ＃我们的'侦听器'节点的名称，以便多个侦听器可以
    ＃同时运行。
     rospy.init_node('listener', anonymous=True)

    rospy.Subscriber('chatter', String, callback)

    # spin() simply keeps python from exiting until this node is stopped
    rospy.spin()

if __name__ == '__main__':
    listener()

先执行发布者，再执行订阅者（python xxx.py）

输出为：

[INFO] [WallTime: 1526964838.601590] /listener_1299_1526964825697好帅啊 1526964838.6
[INFO] [WallTime: 1526964838.701610] /listener_1299_1526964825697好帅啊 1526964838.7
[INFO] [WallTime: 1526964838.801621] /listener_1299_1526964825697好帅啊 1526964838.8
[INFO] [WallTime: 1526964838.901650] /listener_1299_1526964825697好帅啊 1526964838.9
[INFO] [WallTime: 1526964839.001606] /listener_1299_1526964825697好帅啊 1526964839.0
[INFO] [WallTime: 1526964839.101618] /listener_1299_1526964825697好帅啊 1526964839.1