python Matplotlib gtk - animate plot with FuncAnimation

Question

I am trying to update a plot within my GTK window with FunkAnimation. I want to click a button to start updating the plot which gets its data from a txt file. The txt-file gets updated constantly. The intent is to plot a temperature profile. Here is the simplified code:

import gtk
from matplotlib.backends.backend_gtkagg import FigureCanvasGTKAgg as FigureCanvas
import matplotlib.animation as animation
from matplotlib import pyplot as plt

class MyProgram():
    def __init__(self):
        some_gtk_stuff
        self.signals = {
                'on_button_clicked': self.create_plot,
        }
        self.builder.connect_signals(self.signals)

        self.vbox = self.builder.get_object('vbox')

        self.figure = plt.figure()
        self.axis = self.figure.add_subplot(1,1,1)
        self.init = 0

    def create_plot(self):                        
        def update_plot(i):
            #read SampleData from txt File
            x = []
            y = []
            readFile = open('SampleData.txt', 'r')
            sepFile = readFile.read().split('\n')
            readFile.close()

            for data in sepFile:
                xy = data.split(',')
                x.append(int(x)
                y.append(int(y)

            self.axis.plot(x, y)

            if (self.init == 0):
                self.canvas = FigureCanvas(self.figure)
                self.vbox.pack_start(self.canvas)
                self.canvas.show()

            ani = animation.FuncAnimation(self.figure, update_plot, interval = 1000)
            self.canvas.draw()
            return ani

MyProgram()
gtk.main()

So I guess, the problem is, that the create_plot function is only called once. The plot window is created in the gui, but it doesn't get updated. I couldn't find a solution for my problem. Adding `return any' as suggested here didn't work.

You can see a working example here , the code is at the bottom of the page.

I'm aware that i have to implement something like threading for the logging and updating at a later time, but i don't even get it to work without.

Any Tips? :)

Answer 1

I think this is what you want to achieve. Note that I changed the way you read your file. The with open() as f: takes care of the file closing operation which you forgot. It is also possible to write the name of the signal handler in the builder file so one can simply say self.builder.connect(self) and omit the self.signals dicitonary.

import gtk
from matplotlib.backends.backend_gtkagg import FigureCanvasGTKAgg as FigureCanvas
import matplotlib.animation as animation
from matplotlib import pyplot as plt

class MyProgram():
    def __init__(self):
        #some_gtk_stuff
        self.signals = {
                'on_button_clicked': self.create_plot,
        }
        self.builder.connect_signals(self.signals)

        self.vbox = self.builder.get_object('vbox')

        self.figure = plt.figure()
        self.axis = self.figure.add_subplot(1,1,1)
        self.canvas = None

    def create_plot(self, button):
        self.ani = animation.FuncAnimation(self.figure, self.update_plot, interval = 1000)


    def update_plot(self, i):
        #read SampleData from txt File
        x = []
        y = []
        with open('SampleData.txt') as f:
            x_raw, y_raw = f.readline().strip().split(',')
            x.append(int(x_raw))
            y.append(int(y_raw))

        self.axis.plot(x, y)

        if not self.canvas:
            self.canvas = FigureCanvas(self.figure)
            self.vbox.pack_start(self.canvas)
            self.canvas.show()

        self.canvas.draw()

MyProgram()
gtk.main()