如何使用 Matplotlib 绘制 3D 圣诞树

系列文章目录

前言

转自：How to draw a 3D Christmas Tree with Matplotlib | by Timur Bakibayev, Ph.D. | Analytics Vidhya | Mediumhttps://medium.com/analytics-vidhya/how-to-draw-a-3d-christmas-tree-with-matplotlib-aabb9bc27864

因为我们把圣诞树安装在暖气电池旁边，所以它很快就死了。所以我决定用 Matplotlib 绘制一棵圣诞树。你不需要为它遮阳避暑，它也不需要任何水。在阿瑞克斯星球，水的供应是有限的。地球上也是如此。

一、步骤

1.1

要在 matplotlib 中绘图，我们需要将其包含在内。

此外，我们还要为 3D 准备所有库。

import math
import matplotlib.pyplot as plt
from mpl_toolkits.mplot3d import Axes3D
fig = plt.figure()
ax = fig.add_subplot(111, projection="3d")

让我们先画一个 3D 圆，确保一切正常。

fig = plt.figure()
ax = fig.add_subplot(111, projection="3d")
k=300
Z = [10 for i in range(k)]
X = [math.cos(i/10) for i in range(k)]
Y = [math.sin(i/10) for i in range(k)]
ax.scatter(X,Y,Z, c="green", marker="^")
plt.show()

不错！这是非常标准的。我们现在只修复 Z 坐标。

现在，应用 Z 坐标使其 3D 化。

Z = [i for i in range(k)]

让我们在顶部缩小圆的半径。

Z = [i for i in range(k)]
X = [math.cos(i/5)*(k-i) for i in range(k)]
Y = [math.sin(i/5)*(k-i) for i in range(k)]

Matplotlib 总是倾向于贴合图形，只需在此处添加这些限制即可：

plt.xlim(-500,500)
plt.ylim(-500,500)

画一些红圈。它们的公式相同，但步长更大。我们还通过在 sin 和 cos 参数上加 2 来移动它，这样它们就不会与树本身相交。

k=300
Z = [i for i in range(k)]
X = [math.cos(i/5)*(k-i) for i in range(k)]
Y = [math.sin(i/5)*(k-i) for i in range(k)]
ax.scatter(X,Y,Z, c="green", marker="^")
k=300
step = 4
Z = [i for i in range(1,k,step)]
X = [math.cos(i/5+2)*(k-i+10) for i in range(1,k,step)]
Y = [math.sin(i/5+2)*(k-i+10) for i in range(1,k,step)]
ax.scatter(X,Y,Z, c="red", marker="o")
plt.xlim(-500,500)
plt.ylim(-500,500)
plt.show()

微调装饰

c = [(i/k,abs(0.5-i/k),i/k) for i in range(1,k,step)]
ax.scatter(X,Y,Z, c=c, marker="o",s=40)

要旋转树形图，我们需要为每一帧绘制树形图，并在 sin 和 cos 参数中添加一些常数。

我们为初始图形和每一帧复制代码。

import math
import matplotlib.pyplot as plt
from matplotlib import animation
from mpl_toolkits.mplot3d import Axes3D
fig = plt.figure(figsize=(8,8))
ax = fig.add_subplot(111, projection="3d")
def init():k=300Z = [i for i in range(k)]X = [math.cos(i/5)*(k-i) for i in range(k)]Y = [math.sin(i/5)*(k-i) for i in range(k)]ax.scatter(X,Y,Z, c="green", marker="^")step = 3c = [(i/k,abs(0.5-i/k),i/k) for i in range(1,k,step)]Z = [i for i in range(1,k,step)]X = [math.cos(i/5+2)*(k-i+10) for i in range(1,k,step)]Y = [math.sin(i/5+2)*(k-i+10) for i in range(1,k,step)]ax.scatter(X,Y,Z, c=c, marker="o",s=40)plt.xlim(-500,500)plt.ylim(-500,500)return fig,
def animate(f):fig.clear()ax = fig.add_subplot(111, projection="3d")k=300Z = [i for i in range(k)]X = [math.cos(i/5+f/10)*(k-i) for i in range(k)]Y = [math.sin(i/5+f/10)*(k-i) for i in range(k)]ax.scatter(X,Y,Z, c="green", marker="^")step = 3c = [(i/k,abs(0.5-i/k),i/k) for i in range(1,k,step)]Z = [i for i in range(1,k,step)]X = [math.cos(i/5+2+f/10)*(k-i+10) for i in range(1,k,step)]Y = [math.sin(i/5+2+f/10)*(k-i+10) for i in range(1,k,step)]ax.scatter(X,Y,Z, c=c, marker="o",s=40)plt.xlim(-500,500)plt.ylim(-500,500)return fig,
ani=animation.FuncAnimation(fig, animate, init_func=init,frames=90, interval=50, blit=True)
ani.save("christmas_tree.mp4")

这就是结果：