Hello everyone.

A users on the networkx mailing list posted this example which is a modification of the matplotlib-pyqt4 implementation which plots a networkx graph.

The problem I am facing with it is that two plot windows open instead of one, one is empty and the other contains the graph.

I can't really put my finger as to why two windows open rather than just one pyqt window with the plot. Any suggestions would be appreciated.

Screenshot of the two plot windows:
http://img259.imageshack.us/img259/8722/picture1ahr.jpg

Code:

#!/usr/bin/env python


# embedding_in_qt4.py --- Simple Qt4 application embedding matplotlib canvases

#

# Copyright (C) 2005 Florent Rougon

#              2006 Darren Dale

#

# This file is an example program for matplotlib. It may be used and

# modified with no restriction; raw copies as well as modified versions

# may be distributed without limitation.


import sys, os, random

from PyQt4 import QtGui, QtCore


from numpy import arange, sin, pi

from matplotlib.backends.backend_qt4agg import FigureCanvasQTAgg as FigureCanvas

from matplotlib.figure import Figure

import networkx as nx


progname = os.path.basename(sys.argv[0])

progversion = "0.1"



class MyMplCanvas(FigureCanvas):

    """Ultimately, this is a QWidget (as well as a FigureCanvasAgg, etc.)."""

    def __init__(self, parent=None, width=5, height=4, dpi=100):

        fig = Figure(figsize=(width, height), dpi=dpi)

        self.axes = fig.add_subplot(111)

        # We want the axes cleared every time plot() is called

        self.axes.hold(False)


        self.compute_initial_figure()


        #

        FigureCanvas.__init__(self, fig)

        self.setParent(parent)


        FigureCanvas.setSizePolicy(self,

                                  QtGui.QSizePolicy.Expanding,

                                  QtGui.QSizePolicy.Expanding)

        FigureCanvas.updateGeometry(self)


    def compute_initial_figure(self):

        pass



class MyStaticMplCanvas(MyMplCanvas):

    """Simple canvas with a sine plot."""

    def compute_initial_figure(self):

        G=nx.path_graph(10)

        pos=nx.spring_layout(G)

        nx.draw(G,pos,ax=self.axes)



class ApplicationWindow(QtGui.QMainWindow):

    def __init__(self):

        QtGui.QMainWindow.__init__(self)

        self.setAttribute(QtCore.Qt.WA_DeleteOnClose)

        self.setWindowTitle("application main window")


        self.file_menu = QtGui.QMenu('&File', self)

        self.file_menu.addAction('&Quit', self.fileQuit,

                                QtCore.Qt.CTRL + QtCore.Qt.Key_Q)

        self.menuBar().addMenu(self.file_menu)


        self.help_menu = QtGui.QMenu('&Help', self)

        self.menuBar().addSeparator()

        self.help_menu.addAction('&About', self.about)


        self.menuBar().addMenu(self.help_menu)



        self.main_widget = QtGui.QWidget(self)


        l = QtGui.QVBoxLayout(self.main_widget)

        sc = MyStaticMplCanvas(self.main_widget, width=5, height=4, dpi=100)

        l.addWidget(sc)


        self.main_widget.setFocus()

        self.setCentralWidget(self.main_widget)


        self.statusBar().showMessage("All hail matplotlib!", 2000)


    def fileQuit(self):

        self.close()


    def closeEvent(self, ce):

        self.fileQuit()


    def about(self):

        QtGui.QMessageBox.about(self, "About %s" % progname,

u"""%(prog)s version %(version)s

Copyright \N{COPYRIGHT SIGN} 2005 Florent Rougon, 2006 Darren Dale


This program is a simple example of a Qt4 application embedding matplotlib

canvases.


It may be used and modified with no restriction; raw copies as well as

modified versions may be distributed without limitation."""

% {"prog": progname, "version": progversion})



qApp = QtGui.QApplication(sys.argv)


aw = ApplicationWindow()

aw.setWindowTitle("%s" % progname)

aw.show()

sys.exit(qApp.exec_())

#qApp.exec_()