如何使 plt.scatter() 中的点一次显示一个？

Question

我正在使用this tutorial of the Barnsley fern 中的代码，我希望能够缓慢地绘制蕨类植物（而不是一次）。 Python 还不是很舒服，我看到函数 plt.pause() 可能会在其他一些答案中起到作用；但是，我不知道如何将 plt.pause() 与 plt.scatter() 结合起来以获得动画 gif 效果。例如，我是否必须将 plt.scatter 合并到 for 循环中？

# importing necessary modules 
import matplotlib.pyplot as plt 
from random import randint 

# initializing the list 
x = [] 
y = [] 

# setting first element to 0 
x.append(0) 
y.append(0) 

current = 0

for i in range(1, 50000): 

    # generates a random integer between 1 and 100 
    z = randint(1, 100) 

    # the x and y coordinates of the equations 
    # are appended in the lists respectively. 

    # for the probability 0.01 
    if z == 1: 
        a = 0; b = 0; c = 0; d = 0.16; e = 0; f = 0
        x.append(0) 
        y.append(d*(y[current])) 

    # for the probability 0.85     
    if z>= 2 and z<= 86: 
        a = 0.85; b = 0.04; c = -0.04; d = 0.85; e = 0; f = 1.6
        x.append(a*(x[current]) + b*(y[current])) 
        y.append(c*(x[current]) + d*(y[current])+f) 

    # for the probability 0.07     
    if z>= 87 and z<= 93: 
        a = 0.2; b = -0.26; c = 0.23; d = 0.22; e = 0; f = 1.6
        x.append(a*(x[current]) + b*(y[current])) 
        y.append(c*(x[current]) + d*(y[current])+f) 

    # for the probability 0.07     
    if z>= 94 and z<= 100: 
        a = -0.15; b = 0.28; c = 0.26; d = 0.24; e = 0; f = 0.44
        x.append(a*(x[current]) + b*(y[current])) 
        y.append(c*(x[current]) + d*(y[current])+f) 

    current = current + 1

plt.figure(figsize=(10,10))

plt.scatter(x, y, s = 0.2, edgecolor ='green') 

这是想要的效果：

Answer 1

我建议你使用FuncAnimation from matplotlib.animation:

你可以在每一帧中只取一个点。您只需设置轴限制以避免图形移动：

fig, ax = plt.subplots(figsize=(10, 10))
ax.set_xlim(min(x), max(x))
ax.set_ylim(min(y), max(y))

def animation(i):
    ax.scatter(x[i], y[i], s=0.2, edgecolor='green')


ani = FuncAnimation(fig, animation, frames=len(x))

plt.show()

编辑 如果您想同时绘制更多点，例如15：

fig, ax = plt.subplots(figsize=(10, 10))
ax.set_xlim(min(x), max(x))
ax.set_ylim(min(y), max(y))

nb_points = 15
# calculate number of frames needed:
# one more frame if remainder is not 0
nb_frames = len(x) // nb_points + (len(x) % nb_points != 0)


def animation(i):
    i_from = i * nb_points
    # are we on the last frame?
    if i_from + nb_points > len(x) - 1:
        i_to = len(x) - 1
    else:
        i_to = i_from + nb_points
    ax.scatter(x[i_from:i_to], y[i_from:i_to], s=0.2, edgecolor='green')


ani = FuncAnimation(fig, animation, frames=nb_frames)

plt.show()