How to use ApproximateTime in python

asked 2013-09-19 04:43:28 -0500

whiterose
148 ●11 ●15 ●19

updated 2014-01-28 17:18:00 -0500

ngrennan
1 ●1 ●1

Hi all,

I'm trying to synchronize (approximately since the stamps of the topics are different) 4 topics.

I have looked at the ApproximateTime example here: http://answers.ros.org/question/60903/timesynchronizer-callback-problem/

But how to do it in python? I have looked at the Python API (http://docs.ros.org/api/message_filters/html/python/) for message filters, but it says nothing about approximatetime.

Thanks in advance.

edit retag flag offensive close merge delete

Comments

Here 10 is the size of queue and 1 is the time in sec to consider for aprox:

one = message_filters.Subscriber('robot0/sonar_0', Range)
two = message_filters.Subscriber('robot0/sonar_1', Range)
ts = message_filters.ApproximateTimeSynchronizer([one, two],10,1)
ts.registerCallback(callback)

Ananthakrishnan ( 2015-10-18 12:51:15 -0500 )edit

add a comment

4

answered 2015-04-05 12:17:33 -0500

Dan Lazewatsky
9115 ●79 ●103 ●160 http://dan.lazewatsky.com/

ApproximateTime was added for python in indigo, and is documented in the indigo version of the api docs.

edit flag offensive delete link

Comments

It seems that this kind of subscriber cannot be unregistered, can you confirm?

Mehdi. ( 2018-12-03 06:37:19 -0500 )edit

you can unsubscribe by iterating over each message_filter's subscription

Assuming you subscribed like this:

self.subs = [message_filters.Subscriber(topic, mtype) for topic, mtype in zip(self.topics, self.types)]
self.ts = message_filters.ApproximateTimeSynchronizer(
            self.subs,
            5,  # queue size
            0.2,
            allow_headerless=False
)  
self.ts.registerCallback(self.cb_logger)

You can unsubscribe like this:

for sub in self.subs:
            sub.sub.unregister()

ljburtz ( 2021-05-28 21:34:31 -0500 )edit

add a comment

1

answered 2017-11-25 17:04:39 -0500

jayess
6155 ●26 ●85 ●92

Just in case someone has some trouble getting going with this, here's an example:

from message_filters import ApproximateTimeSynchronizer, Subscriber

def gotimage(image, camerainfo):
    assert image.header.stamp == camerainfo.header.stamp
    print "got an Image and CameraInfo"

image_sub = Subscriber("/wide_stereo/left/image_rect_color", sensor_msgs.msg.Image)
camera_sub = Subscriber("/wide_stereo/left/camera_info", sensor_msgs.msg.CameraInfo)

ats = ApproximateTimeSynchronizer([image_sub, camera_sub], queue_size=5, slop=0.1))
ats.registerCallback(gotimage)

I adapted this from the docs.

edit flag offensive delete link

add a comment

How to use ApproximateTime in python

Comments

2 Answers

Comments

Question Tools

Stats

Related questions

How to use ApproximateTime in python edit

Comments

2 Answers

Comments

Question Tools

Stats

Related questions

How to use ApproximateTime in python