matplotlib save animation in gif error

I want to save matplotlib animation in gif format.

I succeded to save animation to mp4 format, using code

import matplotlib
matplotlib.use("Agg")

~some codes~

ani = animation.FuncAnimation(fig, draw, update, interval=10, blit=False)
mywriter = animation.FFMpegWriter(fps=60)
ani.save('myanimation.mp4',writer=mywriter)

but if I change myanimation.mp4 to gif format, python makes error

Traceback (most recent call last):
  File "C:\Users\Administrator\Desktop\edison\Edison_v4_backup_1\ver5.py", line 164, in <module>
    ani.save('demoanimation.gif',writer=mywriter);
  File "C:\Python27\lib\site-packages\matplotlib\animation.py", line 718, in save
    writer.grab_frame(**savefig_kwargs)
  File "C:\Python27\lib\site-packages\matplotlib\animation.py", line 204, in grab_frame
    dpi=self.dpi, **savefig_kwargs)
  File "C:\Python27\lib\site-packages\matplotlib\figure.py", line 1421, in savefig
    self.canvas.print_figure(*args, **kwargs)
  File "C:\Python27\lib\site-packages\matplotlib\backend_bases.py", line 2220, in print_figure
    **kwargs)
  File "C:\Python27\lib\site-packages\matplotlib\backends\backend_agg.py", line 497, in print_raw
    renderer._renderer.write_rgba(filename_or_obj)
RuntimeError: Error writing to file

Seeing that I succeded to save in mp4 format, I don't know why it makes error when saving gif format.

Solution 1:

This is because matplotlib does not support GIFs without external programs. If you have imagemagick correctly installed and configured, this should work:

import matplotlib
matplotlib.use('Agg')
import matplotlib.pyplot as plt
import matplotlib.animation
import numpy as np


def init_animation():
    global line
    line, = ax.plot(x, np.zeros_like(x))
    ax.set_xlim(0, 2*np.pi)
    ax.set_ylim(-1,1)

def animate(i):
    line.set_ydata(np.sin(2*np.pi*i / 50)*np.sin(x))
    return line,

fig = plt.figure()
ax = fig.add_subplot(111)
x = np.linspace(0, 2*np.pi, 200)

ani = matplotlib.animation.FuncAnimation(fig, animate, init_func=init_animation, frames=50)
ani.save('/tmp/animation.gif', writer='imagemagick', fps=30)

Solution 2:

Just a reminder, before you use Matplotlib and ImageMagick to convert images or videos to gif, you need to modify Matplotlib's config and add ImageMagick's path.

The following code will show you the config file path of Matplotlib

import matplotlib
matplotlib.matplotlib_fname()

For me the path is

C:\Anaconda\lib\site-packages\matplotlib\mpl-data\matplotlibrc

Then changing animation.convert_path

#animation.convert_path: 'convert' # Path to ImageMagick's convert binary.
                                   # On Windows use the full path since convert
                                   # is also the name of a system tool.

by adding convert.exe path to it

animation.convert_path: C:\Program Files\ImageMagick-6.9.2-Q16-HDRI\convert.exe

Don't forget to remove the # before animation.convert_path.

After the above modification, Matplotlib and ImageMagick will perfectly work and output the gif file you want.

Hope it helps.

Solution 3:

Still had some trouble on Mac OS X, but the answers above pointed me in the right direction.

What I did came down to:

1. brew install imagemagick
2. edit the path file on location /etc/path (sudo vim path) and added the location of bin folder of imagemagick, in my case: /usr/local/Cellar/imagemagick/6.9.6-4/bin

3. changed the settings of matplotlibrc as described above. You can find the location of matplotlibrc by doing in Python: import matplotlib matplotlib.matplotlib_fname() The settings you need to adjust can be found at the end of the file. I adjusted the following ones (commented out). Please note that those settings are not in 'quotes':

   animation.writer : imagemagick

   animation.codec : mpeg4

   animation.bitrate: -1

   animation.frame_format: png

   animation.convert_path: convert