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

[Eric F. <ef...@ha...>]

On 2015/06/23 10:39 AM, Eric Firing wrote:
> 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