Hi,
I think real-time and matplotlib kind of contradict in the first place -
really, matplotlib's performance is terrible. As a rule, it's Assisi generally
a bad idea to let your data file update your GUI. Usually, you want something
like a check every tenth of a second, if data has arrived, and then updating
your GUI accordingly. Otherwise, you will either end up with refresh rates that
are unnecessarily high (e.g. 200fps) or a GUI not reacting to events (e.g.
resizing) by redrawing. So that's two things bad about your approach.
As I explained, you'll have a hard time getting GUI to run in a block, since by
principle, GR blocks can not run in the main thread, and things like Tim's qwt
plot go through death, wind, fire and message passing to get data out of the
blocks' threads and into the GUI thread.
Anyway, with matplotlib and pyqt to wrap the canvas in a qt application and a
little googling you can hack together guis that should work with the qt
generate option - no guarantee though. I'd rather get used to qwt in most cases
than stick with matplotlib...
Greetings,
Marcus
On May 18, 2014 2:25:00 PM CEST, Activecat <active...@gmail.com> wrote:
>On Fri, May 2, 2014 at 8:56 PM, Tom Rondeau <t...@trondeau.com> wrote:
>
>> On Fri, May 2, 2014 at 8:49 AM, Marcus Müller
><marcus.muel...@ettus.com>wrote:
>>
>>> Hi Activecat,
>>>
>>> typical GUI problem; background is that X applications are
>inherently
>>> hard to multithread, which basically requires graphical toolkits to
>run in
>>> a main loop. This conflicts with every block being run in its own
>thread.
>>>
>>> The easiest solution nowadays should be that you generate a QT flow
>graph
>>> in GRC, use PyQT to generate your GUI, register a message handler
>and
>>> integrate matplotlib (there are examples out there, just don't have
>one at
>>> my fingertips right now), and use the message passing interface to
>get data
>>> out of your flow graph into your GUI.
>>>
>>> Greetings,
>>> Marcus
>>>
>>
>> Tim's written a number of blocks like this:
>> https://github.com/osh/gr-pyqt
>>
>> Tom
>>
>
>
>
>The examples (https://github.com/osh/gr-pyqt) are using Qt and Qwt to
>plot
>graphs, not matplotlib.
>(When all the "import pylab" are removed, everything still work as
>usual,
>except for pylab.fftshift ).
>
>In order to stick to matplotlib, I created a custom block, register a
>message handler, and use the message passing interface to get data out
>from
>the flowgraph into the custom block. (Everything is as described by
>Marcus
>as above, except I do not use QT.)
>For this flowgraph, Generate-Option="No GUI"
>
>When I put "self.axes1.figure.canvas.draw()" or "pyplot.draw()" in
>the
>message handler, the same error still happens:
>ERROR: handler caught exception: main thread is not in main loop
>
>Question:
>How to get rid of this error?
>Or, does this mean plotting using matplotlib is not an option ..?
>
>My objective is to plot graphs in realtime using matplotlib.
>I try to stick to Matplotlib because it is the tool I that I am using
>for
>numerical analysis.
>
>
>
>The custom block is coded as:
>
> #!/usr/bin/env python
> # -*- coding: utf-8 -*-
>
> import numpy
> from gnuradio import gr
>
> import pmt
> from matplotlib import pyplot
>
>
> class matplotlib4(gr.sync_block):
>
> def __init__(self):
> gr.sync_block.__init__(self,
> name="matplotlib4",
> in_sig=None,
> out_sig=None)
>
> pyplot.ion()
> self.fig1 = pyplot.figure()
> self.ax1 = self.fig1.add_subplot(2,1,1)
> self.ax1.set_ylabel('Real')
> self.ax1.set_xlabel('time')
> self.ax1.set_ylim(-1.2, 1.2)
> self.ax1.grid(True)
> self.line1, = self.ax1.plot( [0.3]*1000 )
> self.line2, = self.ax1.plot( [0.3]*1000 )
> self.axes1 = pyplot.gca()
> pyplot.draw() # no error of "main thread is not in main
>loop"
> pyplot.show() # no error of "main thread is not in main
>loop"
>
> self.message_port_register_in( pmt.intern("cpdus"))
> self.set_msg_handler(pmt.intern("cpdus"), self.handler4)
>
>
> def handler4( self, msg ):
> samples = pmt.cdr(msg)
> data = numpy.array( pmt.c32vector_elements(samples),
>dtype=numpy.complex64 )
>
> self.line1.set_ydata( data.real )
> self.line2.set_ydata( data.imag )
> #self.fig1.canvas.draw() # handler caught
>exception: main thread is not in main loop
> #pyplot.draw() # handler caught
>exception: main thread is not in main loop
> #self.axes1.figure.canvas.draw() # handler caught
>exception: main thread is not in main loop
> print "handler4(): x.size={}".format( data.size )
>
>
> def work(self, input_items, output_items):
> print "matplotlib4.work(): *** This should not be
>invoked*** "
> return len(input_items[0])
>
>
>
>
>Flowgraph being used for this test:
>
>
>
>
>
>
>
>
>------------------------------------------------------------------------
>
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