[wxPython-users] matplotlib & wxPython question

[Christopher Barker]

1) You might get better luck on the MPL list for this -- you seem to 
have done the embedding right, so it's really an MPL issue.

2) You can change the data on a line object in MPL, without calling plot 
again, so you can re-use all the existing axis, etc, etc. That may be 
faster and more robust.

3) Check out wxMPL for embedding MPL in wx -- it does some of the work 
for you, and has some nice features.

-Chris




Assaf Tal wrote:
> Hi people,
> 
>  
> 
> I hope I've come to the right place - if not please redirect me :).
> 
> I've been trying to get matplotlib & wxPython to work together. I've 
> pretty much succeeded - I've written a program (attached below) which 
> plots a sine function, with a slider controlling the number of cycles. 
> So far so good.
> 
> However, after moving the slider around for several seconds, the program 
> suddenly starts spewing out error messages in the console. The program 
> itself doesn't close or crash, but the plot stops updating itself.
> 
> Can you help me understand the problem and fix it? Is it a memory thing, 
> or perhaps something else?
> 
> Thank you very much for your help!
> 
> 
> Assaf.
> 
> Short note: the "important" parts are the PlotPanel class, with its 
> init_plot_data which gets called every time the slider is moved, and the 
> OnSlider function of the main frame, which is bound to the 
> slider-movement event.
> Other than that, the program consists of two panes separated by a sash.
> I'm using PSPAD to edit my files, and run my programs using Python.exe 
> on a windows XP operating system.
> 
> ---------------------------------------------------------------- Begin 
> attachment 
> ------------------------------------------------------------------------
> 
> #!/usr/bin/env python
> 
> import matplotlib
> matplotlib.use('WXAgg')
> from matplotlib.backends.backend_wxagg import Toolbar, FigureCanvasWxAgg
> 
> from matplotlib.figure import Figure
> import numpy as npy
> import wx
> 
> 
> class PlotPanel(wx.Panel):
>     """ This class represents a basic embelishment on the wx.Panel 
> class, allowing for plots. """
> 
>     def __init__(self, parent):
>         wx.Panel.__init__(self, parent, -1)
>         self.fig = Figure()
>         self.canvas = FigureCanvasWxAgg(self, -1, self.fig)
>         self.figHandle = self.fig.add_subplot(111)
>         # Now put all into a sizer
>         sizer = wx.BoxSizer(wx.VERTICAL)
>         # This way of adding to sizer allows resizing
>         sizer.Add(self.canvas, 1, wx.LEFT|wx.TOP|wx.GROW)
>         self.SetSizer(sizer)
>         self.Fit()
> 
>     def init_plot_data(self,x = [1,2,3,4], y = [1,2,3,4]):
>         self.figHandle.clear()
>         self.figHandle.plot(x,y)
>         self.canvas.draw()
>  
> class MyFrame(wx.Frame):
>     def __init__(self, parent = None, id = -1, pos = (10,10), title = 
> "HelloWorld", size = (800,600)):
>         wx.Frame.__init__(self, parent,id,title, pos, size)
>         self.CreateMenu()
>         # Create a status bar
>         self.CreateStatusBar()
>         # Create the toolbar
>         self.AddToolBar()
>         # Create splitter window
>         self.initpos = 70
>         self.sp = wx.SplitterWindow(self, style=wx.SP_LIVE_UPDATE)
>         # First panel is for the slider
>         self.p1 = wx.Panel(self.sp)
>         # Second panel is for plotting
>         self.p2 = PlotPanel(self.sp)
>         self.p2.Hide()
>         self.p1.SetBackgroundColour("cornflower blue")
>         self.p2.SetBackgroundColour("sky blue")
>         self.sp.Initialize (self.p1)
>         self.sp.SetMinimumPaneSize(10)
>         self.sp.SplitHorizontally(self.p1, self.p2, self.initpos)
>         # Create user input slider
>         self.slider = wx.Slider(self.p1, 100, 25, 1, 100, pos=(10,10), 
> size=(250,-1), style = wx.SL_HORIZONTAL | wx.SL_AUTOTICKS | wx.SL_LABELS)
>         self.slider.SetTickFreq(10,1)
>         self.slider.SetForegroundColour("white")
>         self.Bind(wx.EVT_SLIDER, self.OnSlider, self.slider)
>         self.slider.CentreOnParent()
>         # Create plotting panel
>         self.p2.init_plot_data()
>     
>        
>     def CreateMenu(self):
>         # Define menus
>         menuFile = wx.Menu()
>         menuHelp = wx.Menu()
>         # Add items
>         menuFile.Append(1, "&Open...")
>         menuFile.AppendSeparator()
>         menuFile.Append(3, "E&xit")
>         menuHelp.Append(1, "&About")
>         # Create the menu bar
>         menuBar = wx.MenuBar()
>         menuBar.Append(menuFile,"&File")
>         menuBar.Append(menuHelp,"&Help")
>         # Add to frame
>         self.SetMenuBar(menuBar)
> 
>     def AddToolBar(self):
>         toolbar = self.CreateToolBar(wx.NO_BORDER)
>         toolbar.SetToolBitmapSize((32,32))
>         for each in self.ToolBarData():
>             if not each[0]:
>                 toolbar.AddSeparator()
>             else:
>                 bmp = wx.Image(each[1], 
> wx.BITMAP_TYPE_PNG).ConvertToBitmap()
>                 toolbar.AddSimpleTool(-1,bmp, each[0], each[2]);
>         toolbar.Realize()
>    
>     def ToolBarData(self):
>         return (("Open", "folder.png", "Open a WAV file", self.OnOpen),
>                 ("Play", "media-playback-start.png ", "Play current 
> file", self.OnPlay),
>                 ("", "", "", ""),
>                 ("Help", "help-browser.png", "Browse online help", 
> self.OnHelp))    
> 
>     def OnOpen():
>         pass
>        
>     def OnPlay():
>         pass
>        
>     def OnHelp():
>         pass
>        
>     def OnSlider(self, event):
>         sliderValue = self.slider.GetValue()
>         self.SetStatusText('Ive been moved!')
>         curX = npy.arange(0,10,0.05)
>         curY = npy.sin(sliderValue*curX)
>         self.p2.init_plot_data(curX,curY)
>        
> 
>        
> 
> class App(wx.App):
>     def OnInit(self):
>         self.frame = MyFrame()
>         self.frame.Show()
>         self.SetTopWindow(self.frame)
>         return True
>    
> def main():
>     app = App(False)
>     app.MainLoop()
>    
> if __name__ == '__main__':
>     main()
>    
> 
> 
> ------------------------------------------------------------------- End 
> attachment 
> ------------------------------------------------------------------------

-- 
Christopher Barker, Ph.D.
Oceanographer

Emergency Response Division
NOAA/NOS/OR&R            (206) 526-6959   voice
7600 Sand Point Way NE   (206) 526-6329   fax
Seattle, WA  98115       (206) 526-6317   main reception

Chris.Barker at noaa.gov