{
 "cells": [
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "## Extract Wake County blocks from to a new shapefile\n",
    "This notebook queries the NC statewide block file [link](https://www2.census.gov/geo/tiger/TIGER2010BLKPOPHU/tabblock2010_37_pophu.zip) for those in Wake County (CoFIPS = 183) and saves to a new shapefile. "
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 1,
   "metadata": {},
   "outputs": [],
   "source": [
    "#Package imports\n",
    "import geopandas as gpd\n",
    "from datetime import datetime\n",
    "%matplotlib inline"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 2,
   "metadata": {},
   "outputs": [],
   "source": [
    "#User inputs\n",
    "stateFIPS = '37'\n",
    "countyFIPS = '183'\n",
    "outFilename = './data/spatial/tabblock2010_{}{}_pophu.shp'.format(stateFIPS,countyFIPS)\n",
    "outMetaFilename = outFilename[:-4] + \"_README.txt\""
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 3,
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "Downloading blocks for 37; this take a few minutes...\n"
     ]
    }
   ],
   "source": [
    "#Pull the state block data for the supplied FIPS code\n",
    "print(\"Downloading blocks for {}; this take a few minutes...\".format(stateFIPS))\n",
    "dataURL = 'https://www2.census.gov/geo/tiger/TIGER2010BLKPOPHU/tabblock2010_{}_pophu.zip'.format(stateFIPS)\n",
    "fcBlocks = gpd.read_file(dataURL)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 15,
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "Subsetting data for County FIPS \n"
     ]
    }
   ],
   "source": [
    "#Subset county blocks\n",
    "print(\"Subsetting data for County FIPS \".format(countyFIPS))\n",
    "fcWake_blocks = fcBlocks[fcBlocks.COUNTYFP10 == countyFIPS]"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 18,
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "Saving to ./data/spatial/tabblock2010_37183_pophu.shp\n"
     ]
    }
   ],
   "source": [
    "#Save to a file\n",
    "print(\"Saving to {}\".format(outFilename))\n",
    "fcWake_blocks.to_file(outFilename,filetype='Shapefile')\n",
    "#Save projection to .prj file\n",
    "with open(outFilename[:-3]+'prj','w') as outPrj:\n",
    "    outPrj.write('GEOGCS[\"GCS_North_American_1983\",DATUM[\"D_North_American_1983\",SPHEROID[\"GRS_1980\",6378137.0,298.257222101]],PRIMEM[\"Greenwich\",0.0],UNIT[\"Degree\",0.0174532925199433]]')"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 10,
   "metadata": {},
   "outputs": [],
   "source": [
    "#Write metadata file\n",
    "timeStamp = datetime.now().strftime(\"%Y-%m-%d\")\n",
    "with open(outMetaFilename,'w') as outFN:\n",
    "    outFN.write('''Census block data for FIPS {0}{1} extracted from\n",
    "{2} on {3}\n",
    "'''.format(stateFIPS,countyFIPS,dataURL,timeStamp))"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": []
  }
 ],
 "metadata": {
  "kernelspec": {
   "display_name": "Python 3",
   "language": "python",
   "name": "python3"
  },
  "language_info": {
   "codemirror_mode": {
    "name": "ipython",
    "version": 3
   },
   "file_extension": ".py",
   "mimetype": "text/x-python",
   "name": "python",
   "nbconvert_exporter": "python",
   "pygments_lexer": "ipython3",
   "version": "3.6.8"
  }
 },
 "nbformat": 4,
 "nbformat_minor": 2
}