Consider this code taken from the matplotlib website which animates a sine curve moving to the right.
"""
A simple example of an animated plot
"""
import numpy as np
import matplotlib.pyplot as plt
import matplotlib.animation as animation
fig, ax = plt.subplots()
x = np.arange(0, 2*np.pi, 0.01)
line, = ax.plot(x, np.sin(x))
def animate(i):
line.set_ydata(np.sin(x + i/10.0)) # update the data
return line,
# Init only required for blitting to give a clean slate.
def init():
line.set_ydata(np.ma.array(x, mask=True))
return line,
ani = animation.FuncAnimation(fig, animate, np.arange(1, 200), init_func=init, interval=25, blit=True)
# Commenting out the previous line, and uncommenting the following line gives a static image.
#animation.FuncAnimation(fig, animate, np.arange(1, 200), init_func=init, interval=25, blit=True)
plt.show()
This code is identical to the one I linked on Matplotlib, except for the
two commented lines before plt.show(). Notice that after binding the output of animation.FuncAnimation() to the name ani, this name is not used anywhere in the arguments to plt.show()!
So thinking that this binding was redundant, I deleted the ani= part.
The result was that I got a static image. As long as the output of animation.FuncAnimation is bound to something the animation works as expected. Otherwise not.
what is happening here?
I am using Python 2.7.11 (Anaconda distribution) on Ubuntu 14.04.
