Re: [Matplotlib-users] Dynamic plots with matplotlib and wx on OS X

[Matt N. <new...@ca...>]

Leighton,

This also does not work Win XP....  The issue is that you're
trying to update the data *before* running the MainLoop(). The
puzzle should be why it works on Linux / GTK ;).

There are a few approaches to the better solution, all of which
lead to slightly more complex than your example.  One such
solution is below (and attached), using Start and Stop buttons,
and a timer to periodically update the plot.  I tried to add as
little code to yours as possible, but also changed from
backend_wx to backend_wxagg, because it's significantly faster
and seemed to be your intent.  I'm not sure the logic in
update_data is really what you want, BTW.

You might find the example in MPlot-0.7/examples/test.py at
   http://cars9.uchicago.edu/~newville/Python/MPlot

helpful.  This is a more complete example of dynamically
updating a WXAgg canvas.  It needs better documentation, but
seems pretty close to what you're trying to do.

Hope that helps,

--Matt Newville

import matplotlib
matplotlib.use("WXAgg")
matplotlib.interactive(True)
from matplotlib.backends.backend_wxagg import FigureCanvasWxAgg
from matplotlib.figure import Figure
from matplotlib.axes import Subplot

from Numeric import pi, sin, arange

import wx

class PlotFigure(wx.Frame):
    def __init__(self):
        wx.Frame.__init__(self, None, -1, "Test embedded wxFigure")

        self.fig = Figure((5,4), 75)
        self.canvas = FigureCanvasWxAgg(self, -1, self.fig)

        sizer = wx.BoxSizer(wx.VERTICAL)
        sizer.Add(self.canvas, 1, wx.TOP)

        # create start/stop buttons
        self.button_start = wx.Button(self,-1, " Start ", size=(-1,-1))
        self.button_stop  = wx.Button(self,-1, " Stop  ", size=(-1,-1))

        # bind actions to the buttons
        self.button_start.Bind(wx.EVT_BUTTON,self.OnStart)
        self.button_stop.Bind(wx.EVT_BUTTON, self.OnStop)

        # pack the buttons in the Sizer
        btnsizer = wx.BoxSizer(wx.HORIZONTAL)
        btnsizer.Add(self.button_start,  1, wx.LEFT)
        btnsizer.Add(self.button_stop,  1, wx.LEFT)

        sizer.Add(btnsizer, 0, wx.TOP)
        self.SetSizer(sizer)
        self.Fit()

        # initialize the data here 
        self.init_plot_data()

        # create a timer, used in OnStart / OnStop
        ID_TIMER = wx.NewId()
        wx.EVT_TIMER(self, ID_TIMER, self.onTimer)
        self.timer = wx.Timer(self, ID_TIMER)


    def init_plot_data(self):
        self.a = self.fig.add_subplot(111)
        x = arange(0,2*pi,0.01)           # x-array
        self.a.set_xlim((0., 2*pi))
        self.a.set_ylim((-1., 1.))
        self.line, = self.a.plot(x,x)
        self.npts  = len(x) 
        
    def update_data(self,i):
        self.line.set_ydata(self.line.get_xdata()*0.01*i)
        self.canvas.draw()

    def onTimer(self, event):
        self.count += 1
        if self.count > self.npts:
            self.OnStop()
        else:
            self.update_data(self.count)
            
    def OnStop(self,event=None):
        self.timer.Stop()
        
    def OnStart(self,event=None):
        self.count    = 0
        self.timer.Start(20) #  delay in milliseconds

if __name__ == '__main__':
    app = wx.PySimpleApp(0)
    frame = PlotFigure()
    frame.Show(True)
    app.MainLoop()