Check if a point lies within a polygon

pnpoly.ipynb

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   "source": [
    "# PNPOLY - Point Inclusion in Polygon Test\n",
    "\n",
    "Python implementation based on PNPOLY by W. Randolph Franklin\n",
    "\n",
    "https://wrf.ecse.rpi.edu//Research/Short_Notes/pnpoly.html"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 1,
   "metadata": {},
   "outputs": [],
   "source": [
    "import numpy as np"
   ]
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   "cell_type": "code",
   "execution_count": 2,
   "metadata": {},
   "outputs": [],
   "source": [
    "def inside(point, polygon):\n",
    "    def pnpoly(nvert, vertx, verty, testx, testy):\n",
    "        i, j, c = 0, nvert - 1, 0\n",
    "        for i in range(nvert):\n",
    "            if ( ((verty[i]>testy) != (verty[j]>testy)) and (testx < (vertx[j]-vertx[i]) * (testy-verty[i]) / (verty[j]-verty[i]) + vertx[i]) ):\n",
    "                c = not c\n",
    "            j = i\n",
    "        return c\n",
    "    return pnpoly(polygon.shape[0], polygon[:, 0], polygon[:, 1], point[0], point[1])"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 3,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": [
       "True"
      ]
     },
     "execution_count": 3,
     "metadata": {},
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   ],
   "source": [
    "point = np.array([1.5, 1.5])\n",
    "polygon = np.array([[1, 1], [1, 2], [2, 2], [2, 1]]);\n",
    "\n",
    "inside(point, polygon)"
   ]
  }
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