How to animate two plots with Matplotlib

animation_demo2_matplotlib.py

import numpy as np
from matplotlib.animation import FuncAnimation
import matplotlib.pyplot as plt

x = np.arange(0, 10*np.pi, 0.01)
y_sin = np.sin(x)
y_cos = np.cos(x)

fig = plt.figure()
ax1 = plt.subplot(2, 1, 1)
ax2 = plt.subplot(2, 1, 2)

data_skip = 50


def init_func():
    ax1.clear()
    ax2.clear()
    ax1.set_xlabel('pi')
    ax1.set_ylabel('sin(pi)')
    ax2.set_xlabel('pi')
    ax2.set_ylabel('cos(pi)')
    ax1.set_xlim((x[0], x[-1]))
    ax1.set_ylim((-1, 1))
    ax2.set_xlim((x[0], x[-1]))
    ax2.set_ylim((-1, 1))


def update_plot(i):
    # ax.clear()
    ax1.plot(x[i:i+data_skip], y_sin[i:i+data_skip], color='k')
    ax1.scatter(x[i], y_sin[i], marker='o', color='r')
    ax2.plot(x[i:i+data_skip], y_cos[i:i+data_skip], color='k')
    ax2.scatter(x[i], y_cos[i], marker='o', color='r')


anim = FuncAnimation(fig,
                     update_plot,
                     frames=np.arange(0, len(x), data_skip),
                     init_func=init_func,
                     interval=1)

anim.save('sin_cos.mp4', dpi=150, fps=10, writer='ffmpeg')