matplotlib-users

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

[Leighton P. <lp...@sc...>]

Hi,=0D=0A=0D=0AI'm having difficulty producing dynamic plots on OS X using =
matplotlib=0D=0A0.73.1 and wxPython 2.5.3.1 on OS X 10.3 with Python 2.3.5=0D=
=0A=0D=0AThe code below works with the same configuration on Fedora Core 3,=0D=
=0Aproducing a graph with a line that pivots at the origin.  On OS X,=0D=0A=
however, the frame remains blank and grey until the final plot is drawn,=0D=
=0Awhen the plot takes on the correct final state.=0D=0A=0D=0AI've tried si=
milar examples with bar graphs and scatter plots, and the=0D=0Asame results=
 are produced.  I don't know if this is a problem with=0D=0Amatplotlib or w=
xPython, and any help would be gratefully appreciated.=0D=0A=0D=0AIf you ne=
ed any more info to help, let me know.=0D=0A=0D=0AThe example code is:=0D=0A=0D=
=0A----------------=0D=0A=0D=0Aimport matplotlib=0D=0Amatplotlib.use("WXAgg=
")=0D=0Amatplotlib.interactive(True)=0D=0Afrom matplotlib.backends.backend_=
wx import FigureCanvasWx=0D=0Afrom matplotlib.figure import Figure=0D=0Afro=
m matplotlib.axes import Subplot=0D=0A=0D=0Afrom Numeric import pi, sin, ar=
ange=0D=0A=0D=0Aimport wx=0D=0A=0D=0A=0D=0Aclass PlotFigure(wx.Frame):=0D=0A=
    def __init__(self):=0D=0A        wx.Frame.__init__(self, None, -1, "Tes=
t embedded wxFigure")=0D=0A=0D=0A        self.fig =3D Figure((5,4), 75)=0D=0A=
        self.canvas =3D FigureCanvasWx(self, -1, self.fig)=0D=0A=0D=0A     =
   sizer =3D wx.BoxSizer(wx.VERTICAL)=0D=0A        sizer.Add(self.canvas, 1=
, wx.LEFT|wx.TOP|wx.GROW)=0D=0A        self.SetSizer(sizer)=0D=0A        se=
lf.Fit()=0D=0A=0D=0A    def init_plot_data(self):=0D=0A        self.a =3D s=
elf.fig.add_subplot(111)=0D=0A        x =3D arange(0,2*pi,0.01)           #=
 x-array=0D=0A        self.a.set_xlim((0., 2*pi))=0D=0A        self.a.set_y=
lim((-1., 1.))=0D=0A        self.line, =3D self.a.plot(x,x)=0D=0A=0D=0A    =
def update_data(self, i):=0D=0A        self.line.set_ydata(self.line.get_xd=
ata()*0.01*i)=0D=0A        self.canvas.draw()=0D=0A=0D=0A=0D=0Aif __name__ =
=3D=3D '__main__':=0D=0A    app =3D wx.PySimpleApp(0)=0D=0A    frame =3D Pl=
otFigure()=0D=0A    frame.Show(True)=0D=0A    frame.init_plot_data()=0D=0A =
   for i in arange(1,200):=0D=0A        frame.update_data(i)=0D=0A    app.M=
ainLoop()=0D=0A=0D=0A=0D=0A=0D=0A--=20=0D=0ADr Leighton Pritchard AMRSC=0D=0A=
D131, Plant-Pathogen Interactions, Scottish Crop Research Institute=0D=0AIn=
vergowrie, Dundee, Scotland, DD2 5DA, UK=0D=0AT: +44 (0)1382 562731 x2405 F=
: +44 (0)1382 568578=0D=0AE: lp...@sc...   W: http://bioinf.scri=
=2Esari.ac.uk/lp=0D=0AGPG/PGP: FEFC205C E58BA41B  http://www.keyserver.net =
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RI disclaimer)=0D=0A_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _=
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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()