Coolcrab Coolcrab - 3 months ago 31
Python Question

Animated graph to Animated Gif (Python)

I have made a simple n-body simulator and I plot/animate the movement with the following code:

for i in range(N):
[...]
x = [ Rbod[j][0], Rbod[j][0]]
y = [ Rbod[j][1], Rbod[j][1]]
#print(R1, V1, A1, F12)
if i%10 == 0:
print(i)
pylab.ion()
pylab.scatter( x, y, c=(j/nbodies,j/nbodies,j/nbodies) )
pylab.axis([-400, 400, -400, 400])
pylab.draw()


Now I would really like to save the animation as a gif. Is this possible? The internet vaguely said that it was but not on how to do it with
pylab
.

Example of 4 body interaction:
enter image description here

Answer

I solved it by using ffmpeg, a conversion programme ran trough the commandline. So first I save all the seperate pictures and then make them into a avi and the avi into a gif.

            print(i)
            #pylab.ion()
            pylab.scatter( x, y, c=(j/nbodies,j/nbodies,j/nbodies) )
            pylab.axis([-400, 400, -400, 400])
            #pylab.draw()
            pylab.savefig('picture'+str(i))

os.chdir('C://Users/Alex')
subprocess.call(['ffmpeg', '-i', 'picture%d0.png', 'output.avi'])
subprocess.call(['ffmpeg', '-i', 'output.avi', '-t', '5', 'out.gif'])