{
  "cells": [
    {
      "cell_type": "markdown",
      "metadata": {},
      "source": [
        "\n# 3D voxel / volumetric plot with cylindrical coordinates\n\nDemonstrates using the *x*, *y*, *z* parameters of `.Axes3D.voxels`.\n"
      ]
    },
    {
      "cell_type": "code",
      "execution_count": null,
      "metadata": {
        "collapsed": false
      },
      "outputs": [],
      "source": [
        "import matplotlib.pyplot as plt\nimport numpy as np\n\nimport matplotlib.colors\n\n\ndef midpoints(x):\n    sl = ()\n    for i in range(x.ndim):\n        x = (x[sl + np.index_exp[:-1]] + x[sl + np.index_exp[1:]]) / 2.0\n        sl += np.index_exp[:]\n    return x\n\n# prepare some coordinates, and attach rgb values to each\nr, theta, z = np.mgrid[0:1:11j, 0:np.pi*2:25j, -0.5:0.5:11j]\nx = r*np.cos(theta)\ny = r*np.sin(theta)\n\nrc, thetac, zc = midpoints(r), midpoints(theta), midpoints(z)\n\n# define a wobbly torus about [0.7, *, 0]\nsphere = (rc - 0.7)**2 + (zc + 0.2*np.cos(thetac*2))**2 < 0.2**2\n\n# combine the color components\nhsv = np.zeros(sphere.shape + (3,))\nhsv[..., 0] = thetac / (np.pi*2)\nhsv[..., 1] = rc\nhsv[..., 2] = zc + 0.5\ncolors = matplotlib.colors.hsv_to_rgb(hsv)\n\n# and plot everything\nax = plt.figure().add_subplot(projection='3d')\nax.voxels(x, y, z, sphere,\n          facecolors=colors,\n          edgecolors=np.clip(2*colors - 0.5, 0, 1),  # brighter\n          linewidth=0.5)\n\nplt.show()"
      ]
    },
    {
      "cell_type": "markdown",
      "metadata": {},
      "source": [
        ".. tags::\n   plot-type: 3D,\n   styling: color,\n   level: intermediate\n\n"
      ]
    }
  ],
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