使用Matplotlib制作动图

骑猪看日落 2022-07-25 15:40 224阅读 0赞

我们可以使用Matplotlib的animation模块的FuncAnimation类制作动画，你需要提供的只是一个动态更新变化数据的函数。  
下面是一个最基本的例子：

import numpy as np
    from matplotlib import pyplot as plt
    from matplotlib import animation
    
    fig = plt.figure()
    data = np.random.random((255, 255))
    im = plt.imshow(data, cmap='gray')
    
    # animation function. This is called sequentially
    def animate(i):
        data = np.random.random((255, 255))
        im.set_array(data)
        return [im]
    
    anim = animation.FuncAnimation(fig, animate, frames=200, interval=60, blit=True)
    plt.show()

这个例子中的animation()函数就是动态更新data数据的函数，注意这个函数必须返回一个集合，所以给\[im\]将im转变成一个list进行返回。

下面是从一个教程网站看到模拟雨滴落在地面的例子（[http://www.labri.fr/perso/nrougier/teaching/matplotlib/][http_www.labri.fr_perso_nrougier_teaching_matplotlib]），觉得不错，贴过来。

import numpy as np
    import matplotlib.pyplot as plt
    from matplotlib import animation
    
    # New figure with white background
    fig = plt.figure(figsize=(6,6), facecolor='white')
    
    # New axis over the whole figure, no frame and a 1:1 aspect ratio
    ax = fig.add_axes([0, 0, 1, 1], frameon=False, aspect=1)
    
    # Number of ring
    n = 50
    size_min = 50
    size_max = 50 ** 2
    
    # Ring position
    pos = np.random.uniform(0, 1, (n,2))
    
    # Ring colors
    color = np.ones((n,4)) * (0,0,0,1)
    # Alpha color channel geos from 0(transparent) to 1(opaque)
    color[:,3] = np.linspace(0, 1, n)
    
    # Ring sizes
    size = np.linspace(size_min, size_max, n)
    
    # Scatter plot
    scat = ax.scatter(pos[:,0], pos[:,1], s=size, lw=0.5, edgecolors=color, facecolors='None')
    
    # Ensure limits are [0,1] and remove ticks
    ax.set_xlim(0, 1), ax.set_xticks([])
    ax.set_ylim(0, 1), ax.set_yticks([])
    
    def update(frame):
        global pos, color, size
    
        # Every ring is made more transparnt
        color[:, 3] = np.maximum(0, color[:,3]-1.0/n)
    
        # Each ring is made larger
        size += (size_max - size_min) / n
    
        # Reset specific ring
        i = frame % 50
        pos[i] = np.random.uniform(0, 1, 2)
        size[i] = size_min
        color[i, 3] = 1
    
        # Update scatter object
        scat.set_edgecolors(color)
        scat.set_sizes(size)
        scat.set_offsets(pos)
    
        # Return the modified object
        return scat,
    
    anim = animation.FuncAnimation(fig, update, interval=10, blit=True, frames=200)
    plt.show()

注意这里的返回值是scat,通过给scat添加一个逗号表示返回一个tuple。

![Rain][]

[http_www.labri.fr_perso_nrougier_teaching_matplotlib]: http://www.labri.fr/perso/nrougier/teaching/matplotlib/
[Rain]: /images/20220724/47139246652c41f1b5439742a6330ee2.png