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Hello. I use python. I want to use the loop based on data of Publisher. For example, If I get the data == 1, I need to print "Hello" every 3 seconds, until when I will receive the new message with another data. Please help me.
Subscriber callbacks run on their own thread, so I usually update a variable in the subscriber callback and then use that data in a main loop running in the startup thread. Something like this:
import rospy
class MyNode:
def main(self):
rospy.subscriber('sometopic', SomeMsgType, self.msgCallback)
self.value = None
self.rate = rospy.getParam('~rate', 10.0)
while not rospy.is_shutdown():
... do something with self.value ...
rate.sleep()
def msgCallback(self, newValue):
self.value = newValue
if __name__ == '__main__':
try:
MyNode().main()
except rospy.ROSInterruptException:
pass
You have to set a value for self.value before the while loop runs. Python will throw an exception if you try to access an attribute that doesn't exist. I just chose None so you can determine that no value has been received yet. I'm not sure if I understand your loop question.
You should read the rospy tutorials. Start with the first one.
Asked: 2016-09-01 10:31:43 -0500
Seen: 233 times
Last updated: Sep 01 '16
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