{
 "cells": [
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "from matplotlib import pyplot\n",
    "from shapely.geometry import MultiPolygon\n",
    "from descartes.patch import PolygonPatch\n",
    "\n",
    "%matplotlib inline\n"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "\n",
    "COLOR = {\n",
    "    True:  '#6699cc',\n",
    "    False: '#ff3333'\n",
    "    }\n",
    "\n",
    "def v_color(ob):\n",
    "    return COLOR[ob.is_valid]\n",
    "\n",
    "def plot_coords(ax, ob):\n",
    "    x, y = ob.xy\n",
    "    ax.plot(x, y, 'o', color='#999999', zorder=1)\n"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "    \n",
    "fig = pyplot.figure( 1, figsize=(12,20), dpi=90 )\n",
    "\n",
    "# 1: valid multi-polygon\n",
    "ax = fig.add_subplot(121)\n",
    "\n",
    "a = [(0, 0), (0, 1), (1, 1), (1, 0), (0, 0)]\n",
    "b = [(1, 1), (1, 2), (2, 2), (2, 1), (1, 1)]\n",
    "\n",
    "multi1 = MultiPolygon([ [a, []], [b, []] ])\n",
    "ax.set_title('a) valid')\n",
    "\n",
    "xrange = [-1, 3]\n",
    "yrange = [-1, 3]\n",
    "ax.set_xlim(*xrange)\n",
    "ax.set_xticks([-1, 0, 1, 2, 3])\n",
    "ax.set_ylim(*yrange)\n",
    "ax.set_yticks([-1, 0, 1, 2, 3])\n",
    "ax.set_aspect(1)\n",
    "\n",
    "p0 = multi1[0]\n",
    "plot_coords(ax, p0.exterior)\n",
    "patch = PolygonPatch( p0, facecolor=v_color(multi1), edgecolor=v_color(multi1), alpha=0.5, zorder=2)\n",
    "ax.add_patch(patch)\n",
    "\n",
    "p1 = multi1[1]\n",
    "plot_coords(ax, p1.exterior)\n",
    "patch = PolygonPatch( p1, facecolor=v_color(multi1), edgecolor=v_color(multi1), alpha=0.5, zorder=2)\n",
    "ax.add_patch(patch)\n",
    " \n",
    "    \n",
    "#2: invalid self-touching ring\n",
    "ax = fig.add_subplot(122)\n",
    "\n",
    "c = [(0, 0), (0, 1.5), (1, 1.5), (1, 0), (0, 0)]\n",
    "d = [(1, 0.5), (1, 2), (2, 2), (2, 0.5), (1, 0.5)]\n",
    "\n",
    "multi2 = MultiPolygon([[c, []], [d, []]])\n",
    "\n",
    "ax.set_title('b) invalid')\n",
    "\n",
    "p20 = multi2[0]\n",
    "plot_coords(ax, p20.exterior)\n",
    "patch = PolygonPatch( p20, facecolor=v_color(multi1), edgecolor=v_color(multi1), alpha=0.5, zorder=2)\n",
    "ax.add_patch(patch)\n",
    "\n",
    "p21 = multi2[1]\n",
    "plot_coords(ax, p21.exterior)\n",
    "patch = PolygonPatch( p21, facecolor=v_color(multi1), edgecolor=v_color(multi1), alpha=0.5, zorder=2)\n",
    "ax.add_patch(patch)\n",
    "\n",
    "\n",
    "xrange = [-1, 3]\n",
    "yrange = [-1, 3]\n",
    "ax.set_xlim(*xrange)\n",
    "ax.set_xticks([-1, 0, 1, 2, 3])\n",
    "ax.set_ylim(*yrange)\n",
    "ax.set_yticks([-1, 0, 1, 2, 3])\n",
    "ax.set_aspect(1)\n",
    "\n",
    "pyplot.show()\n"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": []
  }
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