Fiona Demo.ipynb

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     "input": [
      "import fiona\n",
      "help(fiona)"
     ],
     "language": "python",
     "metadata": {},
     "outputs": [
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       "text": [
        "Help on package fiona:\n",
        "\n",
        "NAME\n",
        "    fiona - Fiona is OGR's neat, nimble, no-nonsense API.\n",
        "\n",
        "FILE\n",
        "    c:\\anaconda\\lib\\site-packages\\fiona\\__init__.py\n",
        "\n",
        "DESCRIPTION\n",
        "    Fiona provides a minimal, uncomplicated Python interface to the open\n",
        "    source GIS community's most trusted geodata access library and\n",
        "    integrates readily with other Python GIS packages such as pyproj, Rtree\n",
        "    and Shapely.\n",
        "    \n",
        "    How minimal? Fiona can read features as mappings from shapefiles or\n",
        "    other GIS vector formats and write mappings as features to files using\n",
        "    the same formats. That's all. There aren't any feature or geometry\n",
        "    classes. Features and their geometries are just data.\n",
        "    \n",
        "    A Fiona feature is a Python mapping inspired by the GeoJSON format. It\n",
        "    has `id`, 'geometry`, and `properties` keys. The value of `id` is\n",
        "    a string identifier unique within the feature's parent collection. The\n",
        "    `geometry` is another mapping with `type` and `coordinates` keys. The\n",
        "    `properties` of a feature is another mapping corresponding to its\n",
        "    attribute table. For example:\n",
        "    \n",
        "      {'id': '1',\n",
        "       'geometry': {'type': 'Point', 'coordinates': (0.0, 0.0)},\n",
        "       'properties': {'label': u'Null Island'} }\n",
        "    \n",
        "    is a Fiona feature with a point geometry and one property. \n",
        "    \n",
        "    Features are read and written using objects returned by the\n",
        "    ``collection`` function. These ``Collection`` objects are a lot like\n",
        "    Python ``file`` objects. A ``Collection`` opened in reading mode serves\n",
        "    as an iterator over features. One opened in a writing mode provides\n",
        "    a ``write`` method.\n",
        "    \n",
        "    Usage\n",
        "    -----\n",
        "    \n",
        "    Here's an example of reading a select few polygon features from\n",
        "    a shapefile and for each, picking off the first vertex of the exterior\n",
        "    ring of the polygon and using that as the point geometry for a new\n",
        "    feature writing to a \"points.shp\" file.\n",
        "    \n",
        "      >>> import fiona\n",
        "      >>> with fiona.open('docs/data/test_uk.shp', 'r') as inp:\n",
        "      ...     output_schema = inp.schema.copy()\n",
        "      ...     output_schema['geometry'] = 'Point'\n",
        "      ...     with collection(\n",
        "      ...             \"points.shp\", \"w\",\n",
        "      ...             crs=inp.crs, \n",
        "      ...             driver=\"ESRI Shapefile\", \n",
        "      ...             schema=output_schema\n",
        "      ...             ) as out:\n",
        "      ...         for f in inp.filter(\n",
        "      ...                 bbox=(-5.0, 55.0, 0.0, 60.0)\n",
        "      ...                 ):\n",
        "      ...             value = f['geometry']['coordinates'][0][0]\n",
        "      ...             f['geometry'] = {\n",
        "      ...                 'type': 'Point', 'coordinates': value}\n",
        "      ...             out.write(f)\n",
        "    \n",
        "    Because Fiona collections are context managers, they are closed and (in\n",
        "    writing modes) flush contents to disk when their ``with`` blocks end.\n",
        "\n",
        "PACKAGE CONTENTS\n",
        "    _drivers\n",
        "    collection\n",
        "    crs\n",
        "    errors\n",
        "    inspector\n",
        "    odict\n",
        "    ogrext\n",
        "    rfc3339\n",
        "    tool\n",
        "\n",
        "FUNCTIONS\n",
        "    bounds(ob)\n",
        "        Returns a (minx, miny, maxx, maxy) bounding box.\n",
        "        \n",
        "        The ``ob`` may be a feature record or geometry.\n",
        "    \n",
        "    listlayers(path, vfs=None)\n",
        "        Returns a list of layer names in their index order.\n",
        "        \n",
        "        The required ``path`` argument may be an absolute or relative file or\n",
        "        directory path.\n",
        "        \n",
        "        A virtual filesystem can be specified. The ``vfs`` parameter may be\n",
        "        an Apache Commons VFS style string beginning with \"zip://\" or\n",
        "        \"tar://\"\". In this case, the ``path`` must be an absolute path within\n",
        "        that container.\n",
        "    \n",
        "    open(path, mode='r', driver=None, schema=None, crs=None, encoding=None, layer=None, vfs=None)\n",
        "        Open file at ``path`` in ``mode`` \"r\" (read), \"a\" (append), or\n",
        "        \"w\" (write) and return a ``Collection`` object.\n",
        "        \n",
        "        In write mode, a driver name such as \"ESRI Shapefile\" or \"GPX\" (see\n",
        "        OGR docs or ``ogr2ogr --help`` on the command line) and a schema\n",
        "        mapping such as:\n",
        "        \n",
        "          {'geometry': 'Point',\n",
        "           'properties': [('class', 'int'), ('label', 'str'), \n",
        "                          ('value', 'float')]}\n",
        "        \n",
        "        must be provided. If a particular ordering of properties (\"fields\"\n",
        "        in GIS parlance) in the written file is desired, a list of (key,\n",
        "        value) pairs as above or an ordered dict is required. If no ordering\n",
        "        is needed, a standard dict will suffice.\n",
        "        \n",
        "        A coordinate reference system for collections in write mode can be\n",
        "        defined by the ``crs`` parameter. It takes Proj4 style mappings like\n",
        "        \n",
        "          {'proj': 'longlat', 'ellps': 'WGS84', 'datum': 'WGS84', \n",
        "           'no_defs': True}\n",
        "        \n",
        "        The drivers used by Fiona will try to detect the encoding of data\n",
        "        files. If they fail, you may provide the proper ``encoding``, such\n",
        "        as 'Windows-1252' for the Natural Earth datasets.\n",
        "        \n",
        "        When the provided path is to a file containing multiple named layers\n",
        "        of data, a layer can be singled out by ``layer``.\n",
        "        \n",
        "        A virtual filesystem can be specified. The ``vfs`` parameter may be\n",
        "        an Apache Commons VFS style string beginning with \"zip://\" or\n",
        "        \"tar://\"\". In this case, the ``path`` must be an absolute path\n",
        "        within that container.\n",
        "    \n",
        "    prop_type(text)\n",
        "        Returns a schema property's proper Python type.\n",
        "        \n",
        "        Example:\n",
        "        \n",
        "          >>> prop_type('int')\n",
        "          <class 'int'>\n",
        "          >>> prop_type('str:25')\n",
        "          <class 'str'>\n",
        "    \n",
        "    prop_width(val)\n",
        "        Returns the width of a str type property.\n",
        "        \n",
        "        Undefined for non-str properties. Example:\n",
        "        \n",
        "          >>> prop_width('str:25')\n",
        "          25\n",
        "          >>> prop_width('str')\n",
        "          80\n",
        "\n",
        "DATA\n",
        "    __all__ = ['bounds', 'listlayers', 'open', 'prop_type', 'prop_width']\n",
        "    __version__ = '1.1.4'\n",
        "\n",
        "VERSION\n",
        "    1.1.4\n",
        "\n",
        "\n"
       ]
      }
     ],
     "prompt_number": 1
    },
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     "cell_type": "code",
     "collapsed": false,
     "input": [
      "import fiona\n",
      "with fiona.open('./Fiona/docs/data/test_uk.shp', 'r') as inp:\n",
      "    output_schema = inp.schema.copy()\n",
      "    output_schema['geometry'] = 'Point'\n",
      "    with fiona.collection(\n",
      "             \"points.shp\", \"w\",\n",
      "             crs=inp.crs, \n",
      "             driver=\"ESRI Shapefile\", \n",
      "             schema=output_schema\n",
      "             ) as out:\n",
      "         for f in inp.filter(\n",
      "                 bbox=(-5.0, 55.0, 0.0, 60.0)\n",
      "                 ):\n",
      "             value = f['geometry']['coordinates'][0][0]\n",
      "             f['geometry'] = {\n",
      "                 'type': 'Point', 'coordinates': value}\n",
      "             out.write(f)"
     ],
     "language": "python",
     "metadata": {},
     "outputs": [],
     "prompt_number": 12
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": [
      "import fiona\n",
      "inp = fiona.open('./Fiona/docs/data/states.shp', 'r')"
     ],
     "language": "python",
     "metadata": {},
     "outputs": [
      {
       "ename": "ImportError",
       "evalue": "No module named fiona",
       "output_type": "pyerr",
       "traceback": [
        "\u001b[0;31m---------------------------------------------------------------------------\u001b[0m\n\u001b[0;31mImportError\u001b[0m                               Traceback (most recent call last)",
        "\u001b[0;32m<ipython-input-1-802fac26922d>\u001b[0m in \u001b[0;36m<module>\u001b[0;34m()\u001b[0m\n\u001b[0;32m----> 1\u001b[0;31m \u001b[0;32mimport\u001b[0m \u001b[0mfiona\u001b[0m\u001b[0;34m\u001b[0m\u001b[0m\n\u001b[0m\u001b[1;32m      2\u001b[0m \u001b[0minp\u001b[0m \u001b[0;34m=\u001b[0m \u001b[0mfiona\u001b[0m\u001b[0;34m.\u001b[0m\u001b[0mopen\u001b[0m\u001b[0;34m(\u001b[0m\u001b[0;34m'./Fiona/docs/data/states.shp'\u001b[0m\u001b[0;34m,\u001b[0m \u001b[0;34m'r'\u001b[0m\u001b[0;34m)\u001b[0m\u001b[0;34m\u001b[0m\u001b[0m\n",
        "\u001b[0;31mImportError\u001b[0m: No module named fiona"
       ]
      }
     ],
     "prompt_number": 1
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": [
      "for rec in inp:\n",
      "    print rec[\"properties\"][\"STATE_NAME\"]\n",
      "    state_name = rec[\"properties\"][\"STATE_NAME\"]\n",
      "    print \"./{}.shp\".format(state_name)\n",
      "    of = fiona.open(\"./{}.shp\".format(state_name), \"w\")\n",
      "    of.write(rec)\n",
      "    \n",
      "\n",
      "\n",
      "\n"
     ],
     "language": "python",
     "metadata": {},
     "outputs": [
      {
       "ename": "SyntaxError",
       "evalue": "invalid syntax (<ipython-input-31-f1a5df05a668>, line 6)",
       "output_type": "pyerr",
       "traceback": [
        "\u001b[1;36m  File \u001b[1;32m\"<ipython-input-31-f1a5df05a668>\"\u001b[1;36m, line \u001b[1;32m6\u001b[0m\n\u001b[1;33m    of.write(rec)\u001b[0m\n\u001b[1;37m     ^\u001b[0m\n\u001b[1;31mSyntaxError\u001b[0m\u001b[1;31m:\u001b[0m invalid syntax\n"
       ]
      }
     ],
     "prompt_number": 31
    },
    {
     "cell_type": "markdown",
     "metadata": {},
     "source": [
      "**Exercise:**\n",
      "\n",
      "Create State Flash Cards (PNGs) from a Shapefile of the USA. Each card's state should be zoomed to the full extent.\n",
      "\n",
      "Step 1: Get a list of unique STATE_NAMEs\n",
      "\n",
      "Step 2: Extract each state's geographic feature with a WHERE clause on the STATE_NAME\n",
      "\n",
      "Step 3: Convert each SHP to a PNG"
     ]
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": [],
     "language": "python",
     "metadata": {},
     "outputs": [],
     "prompt_number": 4
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": [],
     "language": "python",
     "metadata": {},
     "outputs": [],
     "prompt_number": 4
    }
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