matplotlib - animation sinus and points #2

#!/usr/bin/env python3

# animated GIF: https://media.giphy.com/media/3og0IR8kl9YxONfB7y/giphy.gif

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, 0.1)
px = np.arange(0, 2*np.pi, (2*np.pi-0.1)/4)

#q = len(x)//4
#px = np.array([x[q*0], x[q*1], x[q*2], x[q*3], x[q*4]])

line, = ax.plot(x, np.sin(x), 'red')
points, = ax.plot(px, np.sin(px), 'go') # 'g' = green, 'o' = circles

def animate(i):
    print(i)
    line.set_ydata(np.sin(x+i))
    points.set_ydata(np.sin(px+i))
    return line, points

# interval=50 gives fps=20 (50ms*20 = 1000ms = 1second)
ani = animation.FuncAnimation(fig, animate, x, interval=50, blit=True)

# display animation - it doesn't stop - you have to close window
plt.show()

# save in file - it may need some time to render and save all frames
ani.save('animation.gif', writer='imagemagick', fps=20)