[Matplotlib-users] backend_webagg for streaming plot updates: examples?

[Eric Firing]

I would like to be able to publish plots that are updated as data are
received by the server. I don't actually want any of the toolbar
interactivity--I just want the updated plot to appear in the browser
automatically. I suspect this can all be done quite easily using the
webagg backend, but I have not yet figured it out by looking at the
embedding_in_webagg.py example and the backend_webagg* code. I expect
that stripping out the toolbar is straightforward, but what I don't
understand is how to achieve the dynamic updates, preferably without
using the animation framework, which I think would add unnecessary
complexity.

Are there any other examples floating around that would help?

Thanks.

Eric

[Eric Firing]

Post by Eric Firing
I would like to be able to publish plots that are updated as data are
received by the server. I don't actually want any of the toolbar
interactivity--I just want the updated plot to appear in the browser
automatically. I suspect this can all be done quite easily using the
webagg backend, but I have not yet figured it out by looking at the
embedding_in_webagg.py example and the backend_webagg* code. I expect
that stripping out the toolbar is straightforward, but what I don't
understand is how to achieve the dynamic updates, preferably without
using the animation framework, which I think would add unnecessary
complexity.
Are there any other examples floating around that would help?
Thanks.
Eric

To answer my own question, in case anyone else is interested, here is a
block of code that can be substituted for the corresponding elements of
the embedding_in_webagg.py example. The whole block goes at the bottom.

-------------------------------------------------
def create_figure():
fig = Figure()
ax = fig.add_subplot(1,1,1)
ax.set_xlim(0, 1)
ax.set_ylim(0, 1)
line, = ax.plot([], [], 'r-')
return fig, line

if __name__ == "__main__":
figure, line = create_figure()
application = MyApplication(figure)

http_server = tornado.httpserver.HTTPServer(application)
http_server.listen(8080)

print("http://127.0.0.1:8080/")
print("Press Ctrl+C to quit")

def update2():
line.set_data(np.random.rand(2, 25))
figure.canvas.draw_idle()

io_loop = tornado.ioloop.IOLoop.instance()
cb = tornado.ioloop.PeriodicCallback(update2, 1000)
cb.start()

io_loop.start()
----------------------------------------------------------

Instead of the using the PeriodicCallback I will probably be using
ZMQStream.on_recv() to register a callback on a socket, but that doesn't
change the basic structure.

Eric