Python Geo_interface applications

The geo_interface (GeoJSON-like) protocol was proposed by Sean Gillies and can be used in Python with:

• Shapely
• Fiona
• descartes
• geojson
• osgeo.ogr
• pygeoif
• PySAL
• ArcPy
• Papyrus
• PyShp, implemented since version 1.1.7 by Christian Lederman (https://github.com/cleder/pyshp)
• Karim Bahgat has created a tempory fork of PyShp that can write new shapes based on geoJSON: Pyshp-fork-speedup-and-geojson-write
• QGIS with the new API with monkey patching by Nathan Woodrow or with generators in GeoJSON, nouveau lingua franca en géomatique ? by Martin Laloux
• mapnik implemented by Dane Springmeyer
• rasterstats
• SpatiaLite implemented here
• PostGIS implemented here
• GeoDjango
• pygml
• geodaisy

Applications

One big advantage of the protocol is its ability to quickly examine the contents of a shapefile as dictionaries:

with Fiona:

    >>> import fiona   
    >>> f = fiona.open('point.shp')  
    >>> f.next()  
    {'geometry': {'type': 'Point', 'coordinates': (161821.09375, 79076.0703125)}, 'id': '0', 'properties': {u'DIP_DIR': 120, u'STRATI_TYP': 1, u'DIP': 30}}
    >>> f.next()['geometry']['coordinates']  
    (161485.09375, 79272.34375)  
    >>> f.next()['properties']['DIP']  
    55  

with PyShp:

    def records(filename):  
        # generator 
        reader = shapefile.Reader(filename)  
        fields = reader.fields[1:]  
        field_names = [field[0] for field in fields]  
        for sr in reader.shapeRecords():  
            geom = sr.shape.__geo_interface__  
            atr = dict(zip(field_names, sr.record))  
            yield dict(geometry=geom,properties=atr)    
        

    >>> import shapefile
    >>> a = records('point.shp')
    >>> a.next()
    {'geometry': {'type': 'Point', 'coordinates': (161821.09375, 79076.0703125)}, 'properties': {'DIP_DIR': 120, 'STRATI_TYP': 1, 'DIP': 30}}
    >>> a.next()['geometry']['coordinates']
    (161485.09375, 79272.34375)
    >>> a.next()['properties']['DIP']
    55
    

with osgeo.ogr

    def records(file):  
        # generator 
        reader = ogr.Open(file)
        layer = reader.GetLayer(0)
        for i in range(layer.GetFeatureCount()):
            feature = layer.GetFeature(i)
            yield json.loads(feature.ExportToJson())
            
    >>> from osgeo import ogr
    >>> a = records('point.shp')
    >>> a.next()
    {'geometry': {'type': 'Point', 'coordinates': (161821.09375, 79076.0703125)}, 'properties': {'DIP_DIR': 120, 'STRATI_TYP': 1, 'DIP': 30}}

with PyQGIS API2:

    layer = qgis.utils.iface.activeLayer()  
    def records(layer):  
        fields = layer.pendingFields()   
        field_names = [field.name() for field in fields]   
        for elem in layer.getFeatures():  
              geom= elem.geometry()  
              atr = dict(zip(field_names, elem.attributes()))  
              yield dict(geometry=geom.exportToGeoJSON(),properties=atr)  
              
    c = records(layer) 
    c.next() 
    {'geometry': {'type': 'Point', 'coordinates': (161821.09375, 79076.0703125)}, 'id': '0', 'properties': {u'DIP_DIR': 120, u'STRATI_TYP': 1, u'DIP': 30}}

conversion to shapely or pygeoif geometry

with shapely (Sean Gillies, as with pygeoif of Christian Lederman):

    >>> from shapely.geometry import shape    
    >>> a = records('point.shp') 
    >>> print shape( a.next()['geometry'])
    POINT (161821.09375 79076.0703125)