Quitting matplotlib.pyplot animation gracefully

Question

I have a script that plots data of some photometry apertures, and I want to plot them in an xy plot. I am using matplotlib.pyplot with python 2.5.

The input data is stored in around 500 files and read. I am aware that this is not the most efficient way of inputting the data but that's another issue...

Example code:

import matplotlib.pyplot as plt

xcoords = []
ycoords = []

# lists are populated with data from first file

pltline, = plt.plot(xcoords, ycoords, 'rx')

# then loop populating the data from each file

for file in filelist:
    xcoords = [...]
    ycoords = [...]

pltline.set_xdata(xcoords)
pltline.set_ydata(ycoords)
plt.draw()

As there are over 500 files, I will occasionally want to close the animation window in the middle of the plotting. My code to plot works but it doesn't exit very gracefully. The plot window does not respond to clicking the close button and I have to Ctrl+C out of it.

Can anyone help me find a way to close the animation window while the script is running whilst looking graceful (well more graceful than a series of python traceback errors)?

Answer 1

If you update the data and do the draw in a loop, you should be able to interrupt it. Here's an example (that draws a stationary circle and then moves a line around the perimeter):

from pylab import *
import time

data = []   # make the data
for i in range(1000):
    a = .01*pi*i+.0007
    m = -1./tan(a)
    x = arange(-3, 3, .1)
    y = m*x
    data.append((clip(x+cos(a), -3, 3),clip(y+sin(a), -3, 3)))


for x, y in data:  # make a dynamic plot from the data
    try:
        plotdata.set_data(x, y)
    except NameError:
        ion()
        fig = figure()
        plot(cos(arange(0, 2.21*pi, .2)), sin(arange(0, 2.21*pi, .2)))
        plotdata = plot(x, y)[0]
        xlim(-2, 2)
        ylim(-2, 2)
    draw()
    time.sleep(.01)

I put in the time.sleep(.01) command to be extra sure that I could break the run, but in my tests (running Linux) it wasn't necessary.