如何在 Matplotlib 的 3D 图中绘制矢量上的箭头？

import numpy as np
import matplotlib.pyplot as plt
from mpl_toolkits.mplot3d import Axes3D
from matplotlib.patches import FancyArrowPatch
from mpl_toolkits.mplot3d import proj3d

class Arrow3D(FancyArrowPatch):
    def __init__(self, xs, ys, zs, *args, **kwargs):
        FancyArrowPatch.__init__(self, (0,0), (0,0), *args, **kwargs)
        self._verts3d = xs, ys, zs

    def draw(self, renderer):
        xs3d, ys3d, zs3d = self._verts3d
        xs, ys, zs = proj3d.proj_transform(xs3d, ys3d, zs3d, renderer.M)
        self.set_positions((xs[0],ys[0]),(xs[1],ys[1]))
        FancyArrowPatch.draw(self, renderer)

# 数据生成和特征向量计算
...

# 绘图
fig = plt.figure(figsize=(15,15))
ax = fig.add_subplot(111, projection='3d')
...
for v in eig_vec:
    a = Arrow3D([mean_x, v[0]], [mean_y, v[1]],
                [mean_z, v[2]], mutation_scale=20,
                lw=3, arrowstyle="-|>", color="r")
    ax.add_artist(a)
...