pymod_uvec.py

import matplotlib.pyplot as plt
def create():
    fig = plt.figure()
    ax = fig.gca(projection='3d')
    ax.set_aspect("equal")
    draw_sphere( ax )
    return ax

import numpy as np
def draw_sphere( ax ):
    u, v = np.mgrid[0:2*np.pi:20j, 0:np.pi:10j]
    x = np.cos(u) * np.sin(v)
    y = np.sin(u) * np.sin(v)
    z = np.cos(v)
    ax.plot_wireframe(x, y, z, color="r")
    ax.scatter([0], [0], [0], color="g", s=100)

#draw cube
# from itertools import product, combinations
# r = [-1, 1]
# for s, e in combinations(np.array(list(product(r, r, r))), 2):
#     if np.sum(np.abs(s - e)) == (r[1] - r[0]):
#         ax.plot3D(*zip(s, e), color="b")

#draw a vector
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)