资源说明：Fiona reads and writes geographic data files

=====
Fiona
=====

Fiona reads and writes geographic data files and thereby helps Python programmers
integrate geographic information systems with other computer systems. Fiona
contains extension modules that link the Geospatial Data Abstraction Library (`GDAL`_).

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Fiona is designed to be simple and dependable. It focuses on reading and
writing data in standard Python IO style and relies upon familiar Python types
and protocols such as files, dictionaries, mappings, and iterators instead of
classes specific to GDAL's OpenGIS Reference Implementation (OGR). Fiona can read and write real-world data using
multi-layered GIS formats and zipped virtual file systems and integrates
readily with other Python GIS packages such as pyproj_, Rtree_, and Shapely_.

Fiona is supported only on CPython versions 3.6+.

Why the name "Fiona"? Because Fiona Is OGR's Neat and Nimble API for Python programmers. And a Shrek reference made us laugh.

For more details, see:

* Fiona `home page `__
* `Docs and manual `__
* `Examples `__

For support and help:

* Main `user discussion group `__

For project discussions, see:

* `Developers discussion group `__

Usage
=====

Collections
-----------

Records are read from and written to ``file``-like `Collection` objects
returned from the ``fiona.open()`` function.  Records are mappings modeled on
the GeoJSON format. They don't have any spatial methods of their own, so if you
want to do anything fancy with them you will probably need Shapely or something
like it. Here is an example of using Fiona to read some records from one data
file, change their geometry attributes, and write them to a new data file.

.. code-block:: python

    import fiona

    # Open a file for reading. We'll call this the "source."

    with fiona.open('tests/data/coutwildrnp.shp') as src:

        # The file we'll write to, the "destination", must be initialized
        # with a coordinate system, a format driver name, and
        # a record schema.  We can get initial values from the open
        # collection's ``meta`` property and then modify them as
        # desired.

        meta = src.meta
        meta['schema']['geometry'] = 'Point'

        # Open an output file, using the same format driver and
        # coordinate reference system as the source. The ``meta``
        # mapping fills in the keyword parameters of fiona.open().

        with fiona.open('test_write.shp', 'w', **meta) as dst:

            # Process only the records intersecting a box.
            for f in src.filter(bbox=(-107.0, 37.0, -105.0, 39.0)):

                # Get a point on the boundary of the record's
                # geometry.

                f['geometry'] = {
                    'type': 'Point',
                    'coordinates': f['geometry']['coordinates'][0][0]}

                # Write the record out.

                dst.write(f)

    # The destination's contents are flushed to disk and the file is
    # closed when its ``with`` block ends. This effectively
    # executes ``dst.flush(); dst.close()``.

Reading Multilayer data
-----------------------

Collections can also be made from single layers within multilayer files or
directories of data. The target layer is specified by name or by its integer
index within the file or directory. The ``fiona.listlayers()`` function
provides an index ordered list of layer names.

.. code-block:: python

    for layername in fiona.listlayers('tests/data'):
        with fiona.open('tests/data', layer=layername) as src:
            print(layername, len(src))

    # Output:
    # ('coutwildrnp', 67)

Layer can also be specified by index. In this case, ``layer=0`` and
``layer='test_uk'`` specify the same layer in the data file or directory.

.. code-block:: python

    for i, layername in enumerate(fiona.listlayers('tests/data')):
        with fiona.open('tests/data', layer=i) as src:
            print(i, layername, len(src))

    # Output:
    # (0, 'coutwildrnp', 67)

Writing Multilayer data
-----------------------

Multilayer data can be written as well. Layers must be specified by name when
writing.

.. code-block:: python

    with open('tests/data/cowildrnp.shp') as src:
        meta = src.meta
        f = next(src)

    with fiona.open('/tmp/foo', 'w', layer='bar', **meta) as dst:
        dst.write(f)

    print(fiona.listlayers('/tmp/foo'))

    with fiona.open('/tmp/foo', layer='bar') as src:
        print(len(src))
        f = next(src)
        print(f['geometry']['type'])
        print(f['properties'])

        # Output:
        # ['bar']
        # 1
        # Polygon
        # OrderedDict([('PERIMETER', 1.22107), ('FEATURE2', None), ('NAME', 'Mount Naomi Wilderness'), ('FEATURE1', 'Wilderness'), ('URL', 'http://www.wilderness.net/index.cfm?fuse=NWPS&sec=wildView&wname=Mount%20Naomi'), ('AGBUR', 'FS'), ('AREA', 0.0179264), ('STATE_FIPS', '49'), ('WILDRNP020', 332), ('STATE', 'UT')])

A view of the /tmp/foo directory will confirm the creation of the new files.

.. code-block:: console

    $ ls /tmp/foo
    bar.cpg bar.dbf bar.prj bar.shp bar.shx

Collections from archives and virtual file systems
--------------------------------------------------

Zip and Tar archives can be treated as virtual filesystems and Collections can
be made from paths and layers within them. In other words, Fiona lets you read
and write zipped Shapefiles.

.. code-block:: python

    for i, layername in enumerate(fiona.listlayers('zip://tests/data/coutwildrnp.zip')):
        with fiona.open('zip://tests/data/coutwildrnp.zip', layer=i) as src:
            print(i, layername, len(src))

    # Output:
    # (0, 'coutwildrnp', 67)

Fiona can also read from more exotic file systems. For instance, a
zipped shape file in S3 can be accessed like so:

.. code-block:: python

   with fiona.open('zip+s3://mapbox/rasterio/coutwildrnp.zip') as src:
       print(len(src))

   # Output:
   # 67


Fiona CLI
=========

Fiona's command line interface, named "fio", is documented at `docs/cli.rst
`__. Its ``fio
info`` pretty prints information about a data file.

.. code-block:: console

    $ fio info --indent 2 tests/data/coutwildrnp.shp
    {
      "count": 67,
      "crs": "EPSG:4326",
      "driver": "ESRI Shapefile",
      "bounds": [
        -113.56424713134766,
        37.0689811706543,
        -104.97087097167969,
        41.99627685546875
      ],
      "schema": {
        "geometry": "Polygon",
        "properties": {
          "PERIMETER": "float:24.15",
          "FEATURE2": "str:80",
          "NAME": "str:80",
          "FEATURE1": "str:80",
          "URL": "str:101",
          "AGBUR": "str:80",
          "AREA": "float:24.15",
          "STATE_FIPS": "str:80",
          "WILDRNP020": "int:10",
          "STATE": "str:80"
        }
      }
    }

Installation
============

Fiona requires Python versions 3.6+ and GDAL version 1.11-3.0.
To build from a source distribution you will need a C compiler and GDAL and Python
development headers and libraries (libgdal1-dev for Debian/Ubuntu, gdal-dev for
CentOS/Fedora).

To build from a repository copy, you will also need Cython to build C sources
from the project's .pyx files. See the project's requirements-dev.txt file for
guidance.

The `Kyngchaos GDAL frameworks
`__ will satisfy
the GDAL/OGR dependency for OS X, as will Homebrew's GDAL Formula (``brew install
gdal``).

Python Requirements
-------------------

Fiona depends on the modules ``six``, ``cligj``,  and ``munch``.
Pip will fetch these requirements for you, but users installing Fiona from a
Windows installer must get them separately.

Unix-like systems
-----------------

Assuming you're using a virtualenv (if not, skip to the 4th command) and
GDAL/OGR libraries, headers, and `gdal-config`_ program are installed to well
known locations on your system via your system's package manager (``brew
install gdal`` using Homebrew on OS X), installation is this simple.

.. code-block:: console

  $ mkdir fiona_env
  $ virtualenv fiona_env
  $ source fiona_env/bin/activate
  (fiona_env)$ pip install fiona

If gdal-config is not available or if GDAL/OGR headers and libs aren't
installed to a well known location, you must set include dirs, library dirs,
and libraries options via the setup.cfg file or setup command line as shown
below (using ``git``). You must also specify the version of the GDAL API on the
command line using the ``--gdalversion`` argument (see example below) or with
the ``GDAL_VERSION`` environment variable (e.g. ``export GDAL_VERSION=2.1``).

.. code-block:: console

  (fiona_env)$ git clone git://github.com/Toblerity/Fiona.git
  (fiona_env)$ cd Fiona
  (fiona_env)$ python setup.py build_ext -I/path/to/gdal/include -L/path/to/gdal/lib -lgdal install --gdalversion 2.1

Or specify that build options and GDAL API version should be provided by a
particular gdal-config program.

.. code-block:: console

  (fiona_env)$ GDAL_CONFIG=/path/to/gdal-config pip install fiona

Windows
-------

Binary installers are available at
https://www.lfd.uci.edu/~gohlke/pythonlibs/#fiona and coming eventually to PyPI.

You can download a binary distribution of GDAL from `here
`_.  You will also need to download
the compiled libraries and headers (include files).

When building from source on Windows, it is important to know that setup.py
cannot rely on gdal-config, which is only present on UNIX systems, to discover
the locations of header files and libraries that Fiona needs to compile its
C extensions. On Windows, these paths need to be provided by the user.
You will need to find the include files and the library files for gdal and
use setup.py as follows. You must also specify the version of the GDAL API on the
command line using the ``--gdalversion`` argument (see example below) or with
the ``GDAL_VERSION`` environment variable (e.g. ``set GDAL_VERSION=2.1``).

.. code-block:: console

    $ python setup.py build_ext -I -lgdal_i -L install --gdalversion 2.1
    
.. code-block:: console
   
   $ set GDAL_VERSION=3.0
   $ pip install --install-option=build_ext --install-option="-I:\\\\include" --install-option="-lgdal_i" --install-option="-L:\\\\libs" fiona

Note: The following environment variables needs to be set so that Fiona works correctly:

* The directory containing the GDAL DLL (``gdal304.dll`` or similar) needs to be in your
  Windows ``PATH`` (e.g. ``C:\gdal\bin``).
* The gdal-data directory needs to be in your Windows ``PATH`` or the environment variable
  ``GDAL_DATA`` must be set (e.g. ``C:\gdal\bin\gdal-data``).
* The environment variable ``PROJ_LIB`` must be set to the proj library directory (e.g.
  ``C:\gdal\bin\proj6\share``)

The `Appveyor CI build `__
uses the GISInternals GDAL binaries to build Fiona. This produces a binary wheel
for successful builds, which includes GDAL and other dependencies, for users
wanting to try an unstable development version.
The `Appveyor configuration file `__ may be a useful example for
users building from source on Windows.

Support
=======

The primary forum for questions about installation and usage of Fiona is
https://fiona.groups.io/g/main. The authors and other users will answer
questions when they have expertise to share and time to explain. Please take
the time to craft a clear question and be patient about responses.

Please do not bring these questions to Fiona's issue tracker, which we want
to reserve for bug reports and other actionable issues.

Development and testing
=======================

Building from the source requires Cython. Tests require `pytest `_. If the GDAL/OGR
libraries, headers, and `gdal-config`_ program are installed to well known
locations on your system (via your system's package manager), you can do this::

  (fiona_env)$ git clone git://github.com/Toblerity/Fiona.git
  (fiona_env)$ cd Fiona
  (fiona_env)$ pip install cython
  (fiona_env)$ pip install -e .[test]
  (fiona_env)$ py.test

Or you can use the ``pep-518-install`` script::

  (fiona_env)$ git clone git://github.com/Toblerity/Fiona.git
  (fiona_env)$ cd Fiona
  (fiona_env)$ ./pep-518-install

If you have a non-standard environment, you'll need to specify the include and
lib dirs and GDAL library on the command line::

  (fiona_env)$ python setup.py build_ext -I/path/to/gdal/include -L/path/to/gdal/lib -lgdal --gdalversion 2 develop
  (fiona_env)$ py.test

.. _GDAL: https://gdal.org
.. _pyproj: https://pypi.org/project/pyproj/
.. _Rtree: https://pypi.org/project/Rtree/
.. _Shapely: https://pypi.org/project/Shapely/
.. _gdal-config: https://gdal.org/programs/gdal-config.html

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