How to invoke a subscriber's callback periodically?

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Hello everyone,

I would like to sample messages from my sensors' topics every 15 seconds (mostly) synchronically, using message_filters.ApproximateTimeSynchronizer. Is that any possible way to register a callback, that will be invoked, for example, every 15 seconds? I've already check out rospy.Timer, but it seems to be not an appropriate way in my case.

My basic code:

def callback(sensor1, sensor2):
     #write messages into csv


def listener():

    sensor0 = message_filters.Subscriber("/sensor0/topic", Int32)
    sensor1 = message_filters.Subscriber("/sensor1/topic", Int32)

    ts = message_filters.ApproximateTimeSynchronizer([sensor0,sensor1], 10, 0.1)
    ts.registerCallback(callback)
    rospy.spin()