Thread: [Matplotlib-users] Closing a pyplot window under MSWindows and under Linux

Dear all,

Consider the following short program:

from matplotlib.pyplot import title, show
for i in xrange(3):
    title(i+1)
    print "window No. "+str(i+1)+" was closed"
    show()

If I run it under Windows XP, at each show() the program displays a window and
blocks; if I close the window by clicking on the "X" at the top right corner,
the program prints the message "window No. ... was closed" , then opens a new
window, and so on for a total of three iterations.

If I run it under Linux (Ubuntu 9.10, living inside a Virtualbox machine),
everything works the same until I close the first window, after which no new
windows are ever opened and displayed. The program does not die, because all
three messages are sent to console:

window No. 1 was closed
window No. 2 was closed
window No. 3 was closed

My questions for the cognoscenti are:

1. Why this difference?
2. How can I get under Linux the same behaviour as under Windows?

Thanks in advance,

Enzo

OK, I found the answer myself. It appears that multiple calls to show() are at
the moment officially unsupported, although they do work for some backends on
some platforms (see e.g.
http://matplotlib.sourceforge.net/faq/howto_faq.html#use-show ). In particular,
I have found that: 

- With Qt4Agg they work under Windows (where Qt4Agg is the default backend, at
least in the Python(X,Y) distribution) but under Linux they result in an
"Underlying C/C++ object has been deleted" error at line 64 of backend_qt4.py

- With TkAgg they fail silently under Linux (where TkAgg is the default backend,
and under Windows they cause a "Fatal Python error: PyEval_RestoreThread: NULL
tstate" exception

- with GTKAgg, not available in my Windows installation, they work well under
Linux, apart from a deprecation warning on the use of GTK.Tooltips() instead of
the new GTK.Tooltip()

Considering that multiple show() functionality is important for many users (see
e.g.
http://www.mail-archive.com/mat...@li.../msg13099.html
) I'd like to ask the backend developers to try their best and support this
feature on as many platforms as possible.

Enzo

On 4/3/2010 11:19 PM, Enzo Michelangeli wrote:
> multiple show() functionality is important for many users (see
> e.g.
> http://www.mail-archive.com/mat...@li.../msg13099.html
>    

http://matplotlib.sourceforge.net/api/pyplot_api.html#matplotlib.pyplot.ion

hth,
Alan Isaac

Alan G Isaac <alan.isaac@...> writes:
> 
> On 4/3/2010 11:19 PM, Enzo Michelangeli wrote:
> > multiple show() functionality is important for many users (see
> > e.g.
> >
http://www.mail-archive.com/matplotlib-users-5NWGOfrQmneRv+LV9MX5uipxlwaOVQ5f
<at> public.gmane.org/msg13099.html
> >    
> 
> http://matplotlib.sourceforge.net/api/pyplot_api.html#matplotlib.pyplot.ion

>From what I undrstand, ion() doesn't do what I need: it just forces a draw()
after every pyplot command allowing animated plots. Instead, I want the program
 to draw and show a complete plot, then pause allowing me to interact with its
window (e.g., to pan, zoom and/or save a screenshot), then, after I close that
window, proceed to build a new, entirely different plot, show it in a new window
and so on.

Enzo 

On 4/4/2010 3:15 AM, Enzo Michelangeli wrote:
> ion() doesn't do what I need: it just forces a draw()
> after every pyplot command allowing animated plots. Instead, I want the program
>   to draw and show a complete plot, then pause allowing me to interact with its
> window (e.g., to pan, zoom and/or save a screenshot), then, after I close that
> window, proceed to build a new, entirely different plot, show it in a new window
> and so on.
>    


import numpy as np
import matplotlib.pyplot as plt
plt.ion()

for _ in range(3):
     data = np.random.randint(0, 9,(4,))
     fig = plt.figure()
     ax = fig.add_subplot(1,1,1)
     ax.plot(data)
     raw_input("Hit Enter to continue")

hth,
Alan Isaac