python - 动画蒙特卡洛方法 Pi 不同的颜色点

Question

我想要我的 mc 方法计算 pi 的结果的动画；但是内圆点的颜色与其他圆点不同。我怎样才能做到这一点？到目前为止，这是我的代码：

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

def punkt_im_quadrat(a,N): #a is length of square, N number of dots
"""generates random point in [0,a)x[0,a)"""
    x = a * np.random.random_sample((N,2))
    return x #[x,y]

def kreis(radius):
    return np.sqrt(radius - x**2)
x = np.linspace(0,1,100)

#create array of N=10 dots
punkte = punkt_im_quadrat(1,10) #a=1, so radius of circle is one


treffer = [i for i in punkte if i[1] <= np.sqrt(1 - i[0]**2)] #dots in circle
treffer = np.array(treffer)

außerhalb = [i for i in punkte if i not in treffer] #dots not in circle
außerhalb = np.array(außerhalb)


pi = 4 * len(treffer) / np.shape(punkte)[0] 

fig = plt.figure()
fig, ax = plt.subplots()
ax.plot(x,kreis(1))
ax.set_xlim(0,1)
ax.set_ylim(0,1)
ax.set(title=r"MC Sampling for $\pi$", 
      ylabel="y-axis",
      xlabel="x-axis")
#colors = ["r" if [punkte[i][0],punkte[i][1]] in treffer else "b"]
graph, = ax.plot([],[], "ro")

def animate(i):
    graph.set_data((punkte[:i,0],), (punkte[:i,1],))
    return graph,


animation = FuncAnimation(fig, func=animate, frames = range(np.shape(punkte)[0]), interval=20, repeat = False)
plt.show()

如您所见，我尝试使用注释的颜色 if 语句来更改颜色；但它然后说
IndexError：用作索引的数组必须是整数（或布尔）类型

然后我想我可以在动画函数中做一个 if 语句来确定点在哪里。但是当使用graph.set_color它时，它会改变所有点的颜色。

如果有人可以帮助我，我会非常高兴。
提前致谢！

标签： pythonmatplotlibcolorsmatplotlib-animation

Answer 1

a 中的所有标记plot都具有相同的颜色，因此无法正常工作。如果要为不同的点使用不同的颜色，则需要使用scatter()

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

def punkt_im_quadrat(a,N): #a is length of square, N number of dots
    """generates random point in [0,a)x[0,a)"""
    x = a * np.random.random_sample((N,2))
    return x #[x,y]

def kreis(radius):
    return np.sqrt(radius - x**2)
x = np.linspace(0,1,100)

#create array of N=10 dots
punkte = punkt_im_quadrat(1,10) #a=1, so radius of circle is one


treffer = [i for i in punkte if i[1] <= np.sqrt(1 - i[0]**2)] #dots in circle
treffer = np.array(treffer)

außerhalb = [i for i in punkte if i not in treffer] #dots not in circle
außerhalb = np.array(außerhalb)

colors = np.array(["r" if i[1] <= np.sqrt(1 - i[0]**2) else "b" for i in punkte])


pi = 4 * len(treffer) / np.shape(punkte)[0] 

fig, ax = plt.subplots()
ax.plot(x,kreis(1))
ax.set_xlim(0,1)
ax.set_ylim(0,1)
ax.set(title=r"MC Sampling for $\pi$", 
      ylabel="y-axis",
      xlabel="x-axis")
graph = ax.scatter([],[], marker='o', s=30)

def animate(i):
    graph.set_offsets(punkte[:i,:])
    graph.set_facecolor(colors[:i])
    return graph,


animation = FuncAnimation(fig, func=animate, frames = range(np.shape(punkte)[0]), interval=20, repeat = False)