talker_timer.py

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#!/usr/bin/env python
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## Timer-based talker demo that published std_msgs/Strings messages
## to the 'chatter' topic.

import rospy
from std_msgs.msg import String


def publish_callback(event):
    hello_str = "hello world %s" % event.current_real.to_sec()
    rospy.loginfo(hello_str)
    pub.publish(hello_str)


if __name__ == '__main__':
    try:
        rospy.init_node('talker', anonymous=True)
        pub = rospy.Publisher('chatter', String, queue_size=10)
        timer = rospy.Timer(rospy.Duration(1. / 10), publish_callback)  # 10Hz
        rospy.spin()
    except rospy.ROSInterruptException:
        pass