Thread: [Matplotlib-users] Being able to move figure around during time.sleep()

Hi all,

I am experiencing the following difficulty:

My program basically loops and wants to redraw a plot (using imshow() )
every 5 seconds or so. So it looks something like:

ion()
while 1:
     do redraw business..
     time.sleep(5)

The redrawing shows up fine, the only problem is that during the 5 seconds
of sleep, I cannot really move the figure window or really do anything with
it.

I am using  MPL on windows with the 'Qt4Agg' backed, and running this code
from ipython (on the command line). I don't quite understand the threading
model of the GUI kit, vs. the main thread, so could someone enlighten me how
it works roughly, and what I need to do in a multi-threaded application in
order to update a figure periodically, and be able to move it around, and do
things with its figure window.

Thanks in advance for any responses.
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VGC123 wrote:
> I am using  MPL on windows with the 'Qt4Agg' backed, and running this code
> from ipython (on the command line). I don't quite understand the threading
> model of the GUI kit, vs. the main thread, so could someone enlighten me how
> it works roughly, and what I need to do in a multi-threaded application in
> order to update a figure periodically, and be able to move it around, and do
> things with its figure window.

I don't know about QT, or if MPL has an abstraction layer for this, but 
with wx, there is a call:

wx.CallAfter(a_function, some_parameters)

that lets you make a call to the GUI from an external thread, so in your 
case, you would put your computation code is a separate thread, then 
call the updating code in a function from wx.CallAfter.


However, it sounds like you don't really need a separate thread, but 
rather just a non-blocking time delay.

In wx, you'd use a wxTimer for that (or wx.CallLater). I'm sure QT has 
something similar, and maybe MPL has an abstraction layer for the 
toolkits (if it doesn't this would be a nice contribution...)

-Chris





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