随机多边形迭代成椭圆

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


np.random.seed(np.random.randint(1e9))


fig, ax = plt.subplots()


#随机生成N个点的坐标
N = 30
xdata = list(np.random.rand(N)*100)
xdata.append(xdata[0])  # 封闭
ydata = list(np.random.rand(N)*100)
ydata.append(ydata[0]) # 封闭


ln, = plt.plot([], [], 'r*-', animated=True)


ax.set_title("迭代成椭圆",color ='b',fontsize =14)
def init():
    ax.set_xlim(0, 100)
    ax.set_ylim(0, 100)
    return ln, #注意这个逗号。返回的是元组
    
def update(frame):
    for i in range(len(xdata)-1):
        xdata[i] = 0.5*(xdata[i]+xdata[i+1])
        ydata[i] =0.5* (ydata[i]+ydata[i+1])
        
    xdata[-1] = xdata[0]# 封闭
    ydata[-1] = ydata[0]# 封闭


    ln.set_data(xdata, ydata)


    min_x, max_x =  min(xdata), max(xdata)
    span_x = max_x - min_x
    min_y, max_y =  min(ydata), max(ydata)
    span_y = max_y - min_y
    
    ax.set_xlim(min_x- 0.2*span_x , max_x+ 0.2*span_x)
    ax.set_ylim(min_y- 0.2*span_y , max_y+ 0.2*span_y)
    return ln, #注意这个逗号。返回的是元组
    
ani = FuncAnimation(fig, update, frames=range(1000),
                    init_func=init, blit=True, interval=100)
#ani.save('t.gif', fps=20) #可保存动画，fps ：每秒帧数，帧率。
plt.show()#若前面保存了动画，则这里只显示最后一帧