[Matplotlib-users] regarding networkx, matplotlib and pyqt

[Ala Al-S. <sha...@ym...>]

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_()