{
  "cells": [
    {
      "cell_type": "markdown",
      "metadata": {},
      "source": [
        "\n# 3D voxel / volumetric plot with RGB colors\n\nDemonstrates using `.Axes3D.voxels` to visualize parts of a color space.\n"
      ]
    },
    {
      "cell_type": "code",
      "execution_count": null,
      "metadata": {
        "collapsed": false
      },
      "outputs": [],
      "source": [
        "import matplotlib.pyplot as plt\nimport numpy as np\n\n\ndef midpoints(x):\n    sl = ()\n    for _ 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, g, b = np.indices((17, 17, 17)) / 16.0\nrc = midpoints(r)\ngc = midpoints(g)\nbc = midpoints(b)\n\n# define a sphere about [0.5, 0.5, 0.5]\nsphere = (rc - 0.5)**2 + (gc - 0.5)**2 + (bc - 0.5)**2 < 0.5**2\n\n# combine the color components\ncolors = np.zeros(sphere.shape + (3,))\ncolors[..., 0] = rc\ncolors[..., 1] = gc\ncolors[..., 2] = bc\n\n# and plot everything\nax = plt.figure().add_subplot(projection='3d')\nax.voxels(r, g, b, sphere,\n          facecolors=colors,\n          edgecolors=np.clip(2*colors - 0.5, 0, 1),  # brighter\n          linewidth=0.5)\nax.set(xlabel='r', ylabel='g', zlabel='b')\nax.set_aspect('equal')\n\nplt.show()"
      ]
    },
    {
      "cell_type": "markdown",
      "metadata": {},
      "source": [
        ".. tags::\n   plot-type: 3D,\n   styling: color\n\n"
      ]
    }
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