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   "source": [
    "# Lecture 10: Topology"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "**Install the shapely Python package!**  \n",
    "\n",
    "If you have Anaconda installed, open the *Anaconda Prompt* and type in:\n",
    "```\n",
    "conda install -c conda-forge shapely\n",
    "```"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "---"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "## Basic usage of shapely"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "from shapely import geometry\n",
    "\n",
    "point = geometry.Point(5,5)\n",
    "print(point)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "rectangle1 = geometry.Polygon([[0,0], [10,0], [10,10], [0,10]])\n",
    "print(rectangle1)\n"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "from shapely import wkt\n",
    "\n",
    "rectangle2 = wkt.loads('POLYGON ((-4 -4, 4 -4, 4 4, -4 4, -4 -4))')\n",
    "print(rectangle2)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "print('Rectangle1 contains Point: %s' % rectangle1.contains(point))\n",
    "print('Rectangle2 contains Point: %s' % rectangle2.contains(point))\n",
    "print('Rectangle1 contains Rectangle2: %s' % rectangle1.contains(rectangle2))\n",
    "print('Rectangle1 intersects Rectangle2: %s' % rectangle1.intersects(rectangle2))"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "---"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "## Read Shapefile into Shapely objects"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "import shapefile\n",
    "\n",
    "sf = shapefile.Reader('04_megye_region.shp', encoding = 'latin1')\n",
    "print(sf.fields)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "for sr in sf.shapeRecords():\n",
    "    record = sr.record\n",
    "    name = record[0]\n",
    "    \n",
    "    shape = sr.shape\n",
    "    geom = geometry.shape(shape)\n",
    "    \n",
    "    print('%s, Area: %.1f km2, Centroid: %s' % (name.title(), geom.area / 1e6, geom.centroid))"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "pos_budapest = geometry.Point(649918.4, 238457.1)\n",
    "for sr in sf.shapeRecords():\n",
    "    record = sr.record\n",
    "    name = record[0]\n",
    "    \n",
    "    shape = sr.shape\n",
    "    geom = geometry.shape(shape)\n",
    "    \n",
    "    if geom.contains(pos_budapest):\n",
    "        print(name.title())"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "---"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "## Exercises"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "**Exercise 1.** Verify that neither of the county polygons in `04_megye_region.shp` intersect with each other."
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": []
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "**Exercise 2.** Verify that for each city / town  in `08_telepulesek.shp` the county metadata in the attribute table is correct, by checking that the city is in the given county according to the `04_megye_region.shp` file."
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": []
  }
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