Thread: [Matplotlib-users] Animation module: every loop takes more and more time

Please consider this small script:
============================================================
import numpy as np
import matplotlib.pyplot as plt
from matplotlib import animation
from time import time
def init():
 return ax.cla()
def animate(i):
 global t
 r = np.random.random(10)
 c = np.sin(2 * np.pi * r) * np.vstack(np.cos(2 * np.pi * r))
 print(time() - t)
 t = time()
 return ax.contourf(c)
if __name__ == '__main__':
 t = time()
 fig = plt.figure()
 ax = fig.add_subplot(111)
 anim = animation.FuncAnimation(fig, animate, init_func=init,
 frames=100,
 interval=15,
 blit=True)
 anim.save('test.mp4', fps=15, extra_args=['-vcodec', 'libx264'])
============================================================
The output from this script is as follows:
============================================================
0.21799993515
0.375
0.28200006485
0.31200003624
0.26500010490
0.31299996376
0.35899996757
0.32800006866
0.34399986267
0.375
0.40600013732
0.39100003242
0.42200016975
0.46899986267
0.5
0.51600003242
0.5
0.54699993133
0.57800006866
0.57799983024
0.59400010108
0.60899996757
0.64100003242
0.65599989891
0.73399996757
0.71900010108
0.73399996757
0.76600003242
0.79699993133
0.81200003624
1.04699993134
0.86000013351
0.89100003242
0.90600013732
0.92199993133
0.92199993133
1.0
1.10899996758
1.01600003242
1.03099989891
1.06200003624
1.11000013351
1.45299983025
1.21900010109
1.34299993515
1.31299996376
1.35900020599
1.39099979401
1.3900001049
1.43799996376
1.42199993134
1.45300006866
1.48399996758
1.5
1.5
1.54700016975
1.54699993134
1.625
1.625
1.625
1.65700006485
1.68700003624
1.67199993134
1.75
1.73399996758
1.73399996758
1.78200006485
1.81200003624
1.82800006866
1.8599998951
1.84299993515
1.93700003624
1.93799996376
1.98399996758
1.96900010109
2.04699993134
2.03099989891
2.03100013733
2.06299996376
2.06200003624
2.10899996758
2.125
2.17199993134
2.14100003242
2.18700003624
2.21900010109
2.2349998951
2.2650001049
2.28100013733
2.28099989891
2.29600000381
2.32899999619
2.375
2.35899996758
2.42199993134
2.46900010109
2.46799993515
2.48500013351
2.5
2.51600003242
============================================================
So every loops is slower and slower. Now, my original script is more complicated, and when it reaches 100th frame the single loop takes half a minute to finish compared to half a second after the first loop. Can someone suggest what is wrong with the above code, and how to avoid this time aggregation on every loop?
Thanks

On Wed, May 29, 2013 at 3:03 PM, zetah <ot...@hu...> wrote:
> Please consider this small script:
>
>
The init() function only happens once. So, each call to ax.contourf() just
simply adds more contours on top of the previous (you just don't see them
because you don't have masked regions or transparency). I would suggest
doing an ax.cla() in the animate() function before doing ax.contourf().
Cheers!
Ben Root

Benjamin Root wrote:
>The init() function only happens once. So, each call to 
>ax.contourf() just
>simply adds more contours on top of the previous (you just don't 
>see them
>because you don't have masked regions or transparency). I would 
>suggest
>doing an ax.cla() in the animate() function before doing 
>ax.contourf().
It's like you said.
Thanks for assistance :)
Cheers