最近接到老师的新任务——画一个XXX的三维模型图，和师兄交流后大概知道了要做什么，在师兄的建议下成功入了python的坑。

然而网上查了很长时间才在matplotlib的example中找到了这种画圆柱网格的模型图的实例。

实例

import matplotlib.pyplot as plt
import matplotlib.colors
import numpy as np
from mpl_toolkits.mplot3d import Axes3D


def midpoints(x):
   sl = ()
   for i in range(x.ndim):
       x = (x[sl + np.index_exp[:-1]] + x[sl + np.index_exp[1:]]) / 2.0
       sl += np.index_exp[:]
   return x

# prepare some coordinates, and attach rgb values to each
r, theta, z = np.mgrid[0:1:11j, 0:np.pi*2:25j, -0.5:0.5:11j]
x = r*np.cos(theta)
y = r*np.sin(theta)

rc, thetac, zc = midpoints(r), midpoints(theta), midpoints(z)

# define a wobbly torus about [0.7, *, 0]
sphere = (rc - 0.7)**2 + (zc + 0.2*np.cos(thetac*2))**2 < 0.2**2

# combine the color components
hsv = np.zeros(sphere.shape + (3,))
hsv[..., 0] = thetac / (np.pi*2)
hsv[..., 1] = rc
hsv[..., 2] = zc + 0.5
colors = matplotlib.colors.hsv_to_rgb(hsv)

# and plot everything
fig = plt.figure()
ax = fig.gca(projection='3d')
ax.voxels(x, y, z, sphere,
         facecolors=colors,
         edgecolors=np.clip(2*colors - 0.5, 0, 1),  # brighter
         linewidth=0.5)

plt.show()

对于我这种python小白来说（黑人问号？？？）
但一看这效果图，嗯嗯就是它！！！

效果图.png

通过百度看了半天终于懂了这段代码是什么意思了。嗯，没错，除了voxels函数其他都没用。。。。更蛋疼的是竟然百度不到voxels的用法，这个时候help()命令可帮了大忙。

voxels原版说明

    voxels(*args, **kwargs) method of matplotlib.axes._subplots.Axes3DSubplot instance
    ax.voxels([x, y, z,] /, filled, **kwargs)

    Plot a set of filled voxels

    All voxels are plotted as 1x1x1 cubes on the axis, with filled[0,0,0]
    placed with its lower corner at the origin. Occluded faces are not
    plotted.

    Call signatures::

        voxels(filled, facecolors=fc, edgecolors=ec, **kwargs)
        voxels(x, y, z, filled, facecolors=fc, edgecolors=ec, **kwargs)

    .. versionadded:: 2.1

    Parameters
    ----------
    filled : 3D np.array of bool
        A 3d array of values, with truthy values indicating which voxels
        to fill

    x, y, z : 3D np.array, optional
        The coordinates of the corners of the voxels. This should broadcast
        to a shape one larger in every dimension than the shape of `filled`.
        These can be used to plot non-cubic voxels.

        If not specified, defaults to increasing integers along each axis,
        like those returned by :func:`~numpy.indices`.
        As indicated by the ``/`` in the function signature, these arguments
        can only be passed positionally.

    facecolors, edgecolors : array_like, optional
        The color to draw the faces and edges of the voxels. Can only be
        passed as keyword arguments.
        This parameter can be:

          - A single color value, to color all voxels the same color. This
            can be either a string, or a 1D rgb/rgba array
          - ``None``, the default, to use a single color for the faces, and
            the style default for the edges.
          - A 3D ndarray of color names, with each item the color for the
            corresponding voxel. The size must match the voxels.
          - A 4D ndarray of rgb/rgba data, with the components along the
            last axis.

    **kwargs
        Additional keyword arguments to pass onto
        :func:`~mpl_toolkits.mplot3d.art3d.Poly3DCollection`

    Returns
    -------
    faces : dict
        A dictionary indexed by coordinate, where ``faces[i,j,k]`` is a
        `Poly3DCollection` of the faces drawn for the voxel
        ``filled[i,j,k]``. If no faces were drawn for a given voxel, either
        because it was not asked to be drawn, or it is fully occluded, then
        ``(i,j,k) not in faces``.

大概看了下，发现比较重要的参数就是x,y,z和filled。

• filled参数

 filled : 3D np.array of bool
        A 3d array of values, with truthy values indicating which voxels
        to fill

它是一个三维的布尔数组。
注意:一定要是三维的！！！
三个维度的长度分别是你的圆柱形网格在r，θ，z方向上的网格数。以上面的实例为例，实例里r方向有10个网格，θ方向有24个网格，z方向有10个网格，所以sphere是一个（10,24,10）的三维数组。

z方向10个网格.png
最后说一下filled数组的取值影响，filled取True，则表示该网格填充，取Flase则表示不填充。若将实例中的sphere改为全是True的数组，则结果如下图所示。
sphere全是True.png

• x,y,z参数
  每个参数也都是三维数组，这三个参数的定义可以保证你的网格不是正方体，将实例中的三个参数删除后结果如下。

  
  无xyz参数.png