Example using `__geo_interface__`

The __geo_interface__ specification suggested by Sean Gilles (gist) vastly expands the capabilities of Karta by making data interchange with external modules simple. This example shows how the popular shapely package can to used to apply a buffer to a Karta polygon.



In [1]:

    
from karta.examples import greenland
from karta.vector.read import from_shape
import shapely.geometry

Pass the data in the greenland Polygon to shapely.



In [3]:

    
shapely_poly = shapely.geometry.shape(greenland)



In [4]:

    
shapely_poly









    Out[4]:

Use shapely to call the GEOS library's GEOSBuffer function (takes several seconds on my machine).



In [6]:

    
shapely_poly_buffered = shapely_poly.buffer(100e3)
shapely_poly_buffered









    Out[6]:

Convert the data back to a Karta Polygon. Since shapely doesn't handle coordinate systems, we need to set the original coordinate system from the old Polygon.



In [7]:

    
greenland_buffered = from_shape(shapely_poly_buffered)
greenland_buffered._crs = greenland.crs

Example using __geo_interface__

Example using `__geo_interface__`