matplotlib-users Mailing List for matplotlib (Page 2)

Hello.  I'm trying to embed mpl in an wxpython app which is intended
to run repeatedly within a single script.  (It's a workaround for not
being able to use pyplot.show() more than once in a script.)

All seems to work as intended when I don't attach any key press events
(here to just destroy the app) to canvas, but when I do, as in the
script below, for some reason I keep getting errors that appear to
indicate that some remnant of the zombie of the previous app instance
may be sticking around when they shouldn't exist.  Both the script in
question and the (typical) error message are shown below in this
message.

I've tried both on Linux (Debian Lenny) and Mac OS X (Leopard) with
Python 2.5 with the latest stable versions of numpy, matplotlib,
wxpython and whatnot.  I observe similar problems on both
environments.  What am I doing wrong?  Am I not properly handling the
cleanup process before destroying the app at each loop?  I think
wx.App.MainLoop() can be run more than once within a script, so that
should be okay, though I'm not sure if mpl is designed to be used this
way.

A strange thing is that when I close the app by clicking on the 'X' on
the Window frame, I don't reproduce the error.  If anything, I wonder
how to initiate the event that imitates that behavior, but that is
probably a question for the wxpython people...

I'd appreciate any assistance!

Cheers,
Taro



#### BEGIN SCRIPT ####

#!/usr/bin/env python

import wxversion
wxversion.ensureMinimal('2.8')
import matplotlib
matplotlib.use('WXAgg')

from matplotlib.backends.backend_wxagg import FigureCanvasWxAgg as FigureCanvas
from matplotlib.figure import Figure
from numpy import arange, sin, pi
import wx


class CanvasFrame(wx.Frame):

    def __init__(self):
        wx.Frame.__init__(self, None, -1, 'CanvasFrame',size=(550,350))

        self.figure = Figure()
        self.axes = self.figure.add_subplot(111)
        t = arange(0.0, 3.0, 0.01)
        s = sin(2 * pi * t)

        self.axes.plot(t, s)
        self.canvas = FigureCanvas(self, -1, self.figure)
        self.Bind(wx.EVT_CLOSE, self.OnCloseWindow)

        self.canvas.mpl_connect('key_press_event', self.key_press)

        self.sizer = wx.BoxSizer(wx.VERTICAL)
        self.sizer.Add(self.canvas, 1, wx.LEFT | wx.TOP | wx.GROW)
        self.SetSizer(self.sizer)
        self.Fit()

    def key_press(self, event):
        self.Close(True)

    def OnCloseWindow(self, event):
        print 'Window Closed'
        self.Destroy()


class App(wx.App):

    def OnInit(self):
        frame = CanvasFrame()
        frame.Show(True)
        return True


def run_app():
    app = App(redirect=False)
    app.MainLoop()
    del app


for i in range(10):
    run_app()

#### END SCRIPT ####


#### BEGIN ERROR MESSAGE ####

Traceback (most recent call last):
  File "/usr/lib/python2.5/site-packages/matplotlib/backends/backend_wx.py",
line 1316, in _onMotion
    FigureCanvasBase.motion_notify_event(self, x, y, guiEvent=evt)
  File "/usr/lib/python2.5/site-packages/matplotlib/backend_bases.py",
line 1244, in motion_notify_event
    guiEvent=guiEvent)
  File "/usr/lib/python2.5/site-packages/matplotlib/backend_bases.py",
line 899, in __init__
    LocationEvent.__init__(self, name, canvas, x, y, guiEvent=guiEvent)
  File "/usr/lib/python2.5/site-packages/matplotlib/backend_bases.py",
line 817, in __init__
    self._update_enter_leave()
  File "/usr/lib/python2.5/site-packages/matplotlib/backend_bases.py",
line 844, in _update_enter_leave
    last.canvas.callbacks.process('axes_leave_event', last)
  File "/usr/lib/python2.5/site-packages/wx-2.8-gtk2-unicode/wx/_core.py",
line 14314, in __getattr__
    raise PyDeadObjectError(self.attrStr % self._name)
wx._core.PyDeadObjectError: The C++ part of the FigureCanvasWxAgg
object has been deleted, attribute access no longer allowed.

#### END ERROR MESSAGE ####

I just installed matplotlib on Snow Leopard 10.6 with the Qt4 backend (via
macports). However, when I try one of the Qt4 examles:

python
/opt/local/share/py26-matplotlib/examples/user_interfaces/embedding_in_qt4.py

I get the following error message:

Traceback (most recent call last):
  File
"/opt/local/share/py26-matplotlib/examples/user_interfaces/embedding_in_qt4.py",
line 70, in update_figure
    self.draw()
  File
"/opt/local/Library/Frameworks/Python.framework/Versions/2.6/lib/python2.6/site-packages/matplotlib/backends/backend_qt4agg.py",
line 130, in draw
    FigureCanvasAgg.draw(self)
  File
"/opt/local/Library/Frameworks/Python.framework/Versions/2.6/lib/python2.6/site-packages/matplotlib/backends/backend_agg.py",
line 314, in draw
    self.figure.draw(self.renderer)
  File
"/opt/local/Library/Frameworks/Python.framework/Versions/2.6/lib/python2.6/site-packages/matplotlib/artist.py",
line 46, in draw_wrapper
    draw(artist, renderer, *kl)
  File
"/opt/local/Library/Frameworks/Python.framework/Versions/2.6/lib/python2.6/site-packages/matplotlib/figure.py",
line 773, in draw
    for a in self.axes: a.draw(renderer)
  File
"/opt/local/Library/Frameworks/Python.framework/Versions/2.6/lib/python2.6/site-packages/matplotlib/artist.py",
line 46, in draw_wrapper
    draw(artist, renderer, *kl)
  File
"/opt/local/Library/Frameworks/Python.framework/Versions/2.6/lib/python2.6/site-packages/matplotlib/axes.py",
line 1735, in draw
    a.draw(renderer)
  File
"/opt/local/Library/Frameworks/Python.framework/Versions/2.6/lib/python2.6/site-packages/matplotlib/artist.py",
line 46, in draw_wrapper
    draw(artist, renderer, *kl)
  File
"/opt/local/Library/Frameworks/Python.framework/Versions/2.6/lib/python2.6/site-packages/matplotlib/axis.py",
line 742, in draw
    tick.draw(renderer)
  File
"/opt/local/Library/Frameworks/Python.framework/Versions/2.6/lib/python2.6/site-packages/matplotlib/artist.py",
line 46, in draw_wrapper
    draw(artist, renderer, *kl)
  File
"/opt/local/Library/Frameworks/Python.framework/Versions/2.6/lib/python2.6/site-packages/matplotlib/axis.py",
line 196, in draw
    self.label1.draw(renderer)
  File
"/opt/local/Library/Frameworks/Python.framework/Versions/2.6/lib/python2.6/site-packages/matplotlib/text.py",
line 515, in draw
    bbox, info = self._get_layout(renderer)
  File
"/opt/local/Library/Frameworks/Python.framework/Versions/2.6/lib/python2.6/site-packages/matplotlib/text.py",
line 272, in _get_layout
    'lp', self._fontproperties, ismath=False)
  File
"/opt/local/Library/Frameworks/Python.framework/Versions/2.6/lib/python2.6/site-packages/matplotlib/backends/backend_agg.py",
line 158, in get_text_width_height_descent
    font = self._get_agg_font(prop)
  File
"/opt/local/Library/Frameworks/Python.framework/Versions/2.6/lib/python2.6/site-packages/matplotlib/backends/backend_agg.py",
line 195, in _get_agg_font
    fname = findfont(prop)
  File
"/opt/local/Library/Frameworks/Python.framework/Versions/2.6/lib/python2.6/site-packages/matplotlib/font_manager.py",
line 1308, in findfont
    _rebuild()
  File
"/opt/local/Library/Frameworks/Python.framework/Versions/2.6/lib/python2.6/site-packages/matplotlib/font_manager.py",
line 1292, in _rebuild
    fontManager = FontManager()
  File
"/opt/local/Library/Frameworks/Python.framework/Versions/2.6/lib/python2.6/site-packages/matplotlib/font_manager.py",
line 984, in __init__
    self.ttffiles = findSystemFonts(paths) + findSystemFonts()
  File
"/opt/local/Library/Frameworks/Python.framework/Versions/2.6/lib/python2.6/site-packages/matplotlib/font_manager.py",
line 341, in findSystemFonts
    for f in get_fontconfig_fonts(fontext):
  File
"/opt/local/Library/Frameworks/Python.framework/Versions/2.6/lib/python2.6/site-packages/matplotlib/font_manager.py",
line 303, in get_fontconfig_fonts
    status, output = commands.getstatusoutput("fc-list file")
  File
"/opt/local/Library/Frameworks/Python.framework/Versions/2.6/lib/python2.6/commands.py",
line 56, in getstatusoutput
    text = pipe.read()
IOError: [Errno 4] Interrupted system call

Any ideas on what could be causing this?

celil