matplotlib动画

例1.实现移动的正弦曲线

from matplotlib import pyplot as plt
from matplotlib import animation
import numpy as np
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))
    return line,

def init():
    line.set_ydata(np.sin(x))
    return line,

ani = animation.FuncAnimation(fig=fig,
                              func=animate,
                              frames=None,
                              init_func=init,
                              interval=1,
                              blit=False)
plt.show()

注意ani虽然用不到，但不知道为什么不赋值不会实现动画效果。

例2.闪烁的散点图

from matplotlib import pyplot as plt
from matplotlib import animation
import numpy as np
fig, ax = plt.subplots()
x = np.arange(0, 2*np.pi, 0.5)
line = ax.scatter(x, np.sin(x), c='black')


def animate(i):
    if i%2:
        color = 'black'
    else:
        color = 'white'
    next_line = ax.scatter(x, np.sin(x), c=color)
    return next_line


def init():
    return line


ani = animation.FuncAnimation(fig=fig,
                              func=animate,
                              frames=None,
                              init_func=init,
                              interval=1000,
                              blit=False)
def save_as_gif():
    import os
    writer = animation.FFMpegWriter()
    ani.save('line.mp4',writer = writer)

    os.system("ffmpeg -i line.mp4 line.gif")
save_as_gif()
plt.show()

每隔1000毫秒，颜色在白与黑间变换一次，实现闪烁效果。
要保存图片需要安装ffmpeg并且配置到环境变量中。

line.gif

例3.多个子图实现动画效果

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

fig = plt.figure()
ani_list = []
def paint(index):
    ax = fig.add_subplot(3,1,index)
    x = np.arange(0, 2*np.pi, 0.5)
    line = ax.scatter(x, np.sin(x), c='black')

    def animate(i):
        if (i+index) % 2:
            color = 'black'
        else:
            color = 'white'
        next_line = ax.scatter(x, np.sin(x), c=color)
        return next_line

    def init():
        return line

    ani = animation.FuncAnimation(fig=fig,
                                  func=animate,
                                  frames=None,
                                  init_func=init,
                                  interval=1000,
                                  blit=False)
    ani_list.append(ani)#no animation if this line removed


for i in range(3):
    paint(i+1)


plt.show()