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51 lines
2.1 KiB
ReStructuredText
51 lines
2.1 KiB
ReStructuredText
.. _io:
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Reading and Writing Files
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=========================================
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Reading Spatial Data
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---------------------
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*geopandas* can read almost any vector-based spatial data format including ESRI shapefile, GeoJSON files and more using the command::
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geopandas.read_file()
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which returns a GeoDataFrame object. (This is possible because *geopandas* makes use of the great `fiona <http://fiona.readthedocs.io/en/latest/manual.html>`_ library, which in turn makes use of a massive open-source program called `GDAL/OGR <http://www.gdal.org/>`_ designed to facilitate spatial data transformations).
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Any arguments passed to ``read_file()`` after the file name will be passed directly to ``fiona.open``, which does the actual data importation. In general, ``read_file`` is pretty smart and should do what you want without extra arguments, but for more help, type::
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import fiona; help(fiona.open)
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Among other things, one can explicitly set the driver (shapefile, GeoJSON) with the ``driver`` keyword, or pick a single layer from a multi-layered file with the ``layer`` keyword::
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countries_gdf = geopandas.read_file("package.gpkg", layer='countries')
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Where supported in ``fiona``, *geopandas* can also load resources directly from
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a web URL, for example for GeoJSON files from `geojson.xyz <http://geojson.xyz/>`_::
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url = "http://d2ad6b4ur7yvpq.cloudfront.net/naturalearth-3.3.0/ne_110m_land.geojson"
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df = geopandas.read_file(url)
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*geopandas* can also get data from a PostGIS database using the ``read_postgis()`` command.
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Writing Spatial Data
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---------------------
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GeoDataFrames can be exported to many different standard formats using the ``GeoDataFrame.to_file()`` method. For a full list of supported formats, type ``import fiona; fiona.supported_drivers``.
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**Writing to Shapefile**::
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countries_gdf.to_file("countries.shp")
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**Writing to GeoJSON**::
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countries_gdf.to_file("countries.geojson", driver='GeoJSON')
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**Writing to GeoPackage**::
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countries_gdf.to_file("package.gpkg", layer='countries', driver="GPKG")
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cities_gdf.to_file("package.gpkg", layer='cities', driver="GPKG")
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