image - matplotlib imshow(): how to animate?

Question

i found this wonderful short tutorial on animation:

http://jakevdp.github.io/blog/2012/08/18/matplotlib-animation-tutorial/

however i cant produce an animated imshow() plot of same fashion. I tried to replace some lines:

# First set up the figure, the axis, and the plot element we want to animate
fig = plt.figure()
ax = plt.axes(xlim=(0, 10), ylim=(0, 10))
#line, = ax.plot([], [], lw=2)
a=np.random.random((5,5))
im=plt.imshow(a,interpolation='none')
# initialization function: plot the background of each frame
def init():
    im.set_data(np.random.random((5,5)))
    return im

# animation function.  This is called sequentially
def animate(i):
    a=im.get_array()
    a=a*np.exp(-0.001*i)    # exponential decay of the values
    im.set_array(a)
    return im

but i run into errors can you help me get this running? thank you in advance. best,

Answer 1

You're very close, but there's one mistake - init and animate should return iterables containing the artists that are being animated. That's why in Jake's version they return line, (which is actually a tuple) rather than line (which is a single line object). Sadly the docs are not clear on this!

You can fix your version like this:

# initialization function: plot the background of each frame
def init():
    im.set_data(np.random.random((5,5)))
    return [im]

# animation function.  This is called sequentially
def animate(i):
    a=im.get_array()
    a=a*np.exp(-0.001*i)    # exponential decay of the values
    im.set_array(a)
    return [im]