Python/matplotlib:绘制一个三维立方体、一个球体和一个矢量?

I search how to plot something with less instruction as possible with matplotlib but I don't find any help for this in the documentation.

我搜索了如何用更少的指令来绘图，但我在文档中没有找到任何帮助。

I want to plot the following things:

我想画出下面的东西

• a wireframe cube centered in 0 with a side length of 2
• 一个线框立方体以0为中心，边长为2。
• a "wireframe" sphere centered in 0 with a radius of 1
• “线框”球体以0为中心，半径为1。
• a point at coordinates [0, 0, 0]
• 坐标[0,0,0]点
• a vector that starts at this point and goes to [1, 1, 1]
• 一个向量从这个点开始，然后到[1,1,1]

How to do that?

如何做呢?

2 个解决方案

#1

It is a little complicated, but you can draw all the objects by the following code:

这有点复杂，但是您可以通过以下代码来绘制所有对象:

from mpl_toolkits.mplot3d import Axes3D
import matplotlib.pyplot as plt
import numpy as np
from itertools import product, combinations


fig = plt.figure()
ax = fig.gca(projection='3d')
ax.set_aspect("equal")

# draw cube
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 sphere
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")

# draw a point
ax.scatter([0], [0], [0], color="g", s=100)

# 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)

a = Arrow3D([0, 1], [0, 1], [0, 1], mutation_scale=20,
            lw=1, arrowstyle="-|>", color="k")
ax.add_artist(a)
plt.show()

#2

For drawing just the arrow, there is an easier method:-

对于只画箭头，有一个更简单的方法:-。

from mpl_toolkits.mplot3d import Axes3D
import matplotlib.pyplot as plt
fig = plt.figure()
ax = fig.gca(projection='3d')
ax.set_aspect("equal")

#draw the arrow
ax.quiver(0,0,0,1,1,1,length=1.0)

plt.show()

quiver can actually be used to plot multiple vectors at one go. The usage is as follows:- [ from http://matplotlib.org/mpl_toolkits/mplot3d/tutorial.html?highlight=quiver#mpl_toolkits.mplot3d.Axes3D.quiver]

quiver实际上可以用来在一个地方绘制多个向量。其用法如下:-[从http://matplotlib.org/mpl_toolkits/mplot3d/tutori.html?

quiver(X, Y, Z, U, V, W, **kwargs)

quiver(X, Y, Z, U, V, W， **kwargs)

Arguments:

参数:

X, Y, Z: The x, y and z coordinates of the arrow locations

X Y Z:箭头位置的X Y Z坐标。

U, V, W: The x, y and z components of the arrow vectors

U, V, W:矢量的x, y和z分量。

The arguments could be array-like or scalars.

这些参数可能是类似arrayoid或标量的。

Keyword arguments:

关键字参数:

length: [1.0 | float] The length of each quiver, default to 1.0, the unit is the same with the axes

长度:[1.0 |浮动]每个抖动的长度，默认为1.0，单位与坐标轴相同。

arrow_length_ratio: [0.3 | float] The ratio of the arrow head with respect to the quiver, default to 0.3

arrow_length_ratio:[0.3 |浮动]箭头与箭筒的比率，默认为0.3。

pivot: [ ‘tail’ | ‘middle’ | ‘tip’ ] The part of the arrow that is at the grid point; the arrow rotates about this point, hence the name pivot. Default is ‘tail’

pivot: [' tail ' | ' middle ' | ' tip ']在网格点上的箭头的一部分;箭头绕着这个点旋转，因此得名枢轴。默认是“尾巴”

normalize: [False | True] When True, all of the arrows will be the same length. This defaults to False, where the arrows will be different lengths depending on the values of u,v,w.

normalize: [False | True]当True时，所有的箭头都是相同的长度。这个默认值为False，箭头的长度取决于u,v,w的值。