subplots and forked show()

Hi, I am not in interactive mode, I am writing scripts that

    > handle a bunch of data and then plot it all. However, when
    > show() is called, the script stops and waits for all the
    > windows it opens to be closed before continuing. What I was
    > hoping for was a way to have the plots be drawn in windows
    > that were no longer hooked into the script, such that the
    > script could continue running (to completion) regardless of
    > what happened to the open windows. I did try 'draw()',
    > which does not appear to open any new windows.

Hi Mark,

Thanks for the explanation. Now I understand what you are trying to
do. You are right about draw, all it does is redraw an existing
figure, eg if you have changed some data in it.

You have to get a little bit into the GTK API / event handling
mechanism to do this right. One way is to use the full blown gtk API
with matplotlib, as in examples/embedding_in_gtk*.py.

The easier way is to just use as much of the API as you need, and take
over the function of the backend 'show' function. You'll be doing an
end run around the matplotlib.matlab figure manager, which means some
of these won't work (like gcf, close, etc.). That's OK, because you
won't be using the matplotlib.matlab interface. Do not import
matplotlib.matlab with this approach as the result is undefined!

There are a few things you need to do

  * Define function(s) / class(es) which create your figures

  * Define a main function which call these functions as necessary.
    Return False from this function

  * Add main to the gtk idle handler. Returning False in 'main' will
    cause this function to be called only once.

  * Start the gtk mainloop yourself. After gtk is started, your
    'main' function will be called and you're off to the races.

  * If there is something you want from matplotlib.matlab, say the
    'axis' command, just look at the src code to see how axis is
    implemented with the matplotlib API and make those calls yourself.

You may want to spend some time with the pygtk class reference at
http://www.pygtk.org/pygtk2reference/gtk-class-reference.html and the
matplotlib class reference at
http://matplotlib.sourceforge.net/classdocs.html. In the example
below

  * canvas inherits from gtk.DrawingArea and
    backends.FigureCanvasGTK (which in turn derives from
    backend_bases.FigureCanvasBase)

  * manager is a backends.backend_gtk.FigureManagerGTK
    which inherits from backend_bases.FigureManagerBase

  * manager.window is a gtk.Window() (you can also hide or close this
    window with pygtk API calls)

  * ax is a axes.Subplot which inherits from axes.Axes

Here is an example

#!/usr/bin/env python
import matplotlib
matplotlib.use('GTKAgg')
from matplotlib.backends.backend_gtkagg import new_figure_manager
from matplotlib.numerix import *
import gtk

def main(*args):

    manager1 = new_figure_manager(1)
    canvas1 = manager1.canvas
    fig1 = canvas1.figure
    ax1 = fig1.add_subplot(111)
    ax1.plot([1,2,3])
    manager1.window.show() # non blocking

    manager2 = new_figure_manager(2)
    canvas2 = manager2.canvas
    fig2 = canvas2.figure
    ax2 = fig2.add_subplot(111)
    ax2.plot([6,5,4])
    manager2.window.show()
    return False

gtk.idle_add(main)
gtk.mainloop()

Hi,

I think I recall I observed the requested behavior (i.e. get hand back
in interractive window or script after a show()) in previous version of
matplotlib.
I remember this cause reproducing this non-blocking behavior of show()
has proven to be a little bit hard to reproduce when developing FltkAgg
backend (I have done it using thread, and it works, so a solution would
be to use this backend when it is integrated).
But with TkAgg and GTKAgg, cvs version, on linux, it does not work
anymore (i.e. show() do not return hand, as mentioned)
I tested some earlier version (0.54 on windows, TkAgg) to see if I have
so false souvenir, but it indeed work as Mark want (i.e. show() is
non-blocking )...So I guess something has changed in the show()
mechanism since, maybe to deal with the new event mechanism?

Best regards,

Greg.

···

On Wed, 2004-07-28 at 14:11, John Hunter wrote:

    > Hi, I am not in interactive mode, I am writing scripts that
    > handle a bunch of data and then plot it all. However, when
    > show() is called, the script stops and waits for all the
    > windows it opens to be closed before continuing. What I was
    > hoping for was a way to have the plots be drawn in windows
    > that were no longer hooked into the script, such that the
    > script could continue running (to completion) regardless of
    > what happened to the open windows. I did try 'draw()',
    > which does not appear to open any new windows.

Hi Mark,

Thanks for the explanation. Now I understand what you are trying to
do. You are right about draw, all it does is redraw an existing
figure, eg if you have changed some data in it.