plpygis 0.0.1

PostGIS Python tools

plpygis is a Python conveter to and from the PostGIS geometry type, WKT, EWKT, WKB, EWKB, GeoJSON and Shapely geometries, or using __geo_interface__. plpygis is intended for use in PL/Python functions.

Basic usage

The Geometry class can be used to convert to and from PostGIS geometries. The following example will take a PostGIS multipolygon geometry named geom and find its largest component polygon.

Geometry() can convert direclty a Postigs geometry that has been passed as a parameter to a PL/Python function. A Geometry that is returned from the PL/Python function will automatically be converted back to a PostGIS geometry.

CREATE OR REPLACE FUNCTION largest_poly(geom geometry)
  RETURNS geometry
AS $$
  from plpygis import Geometry
  polygons = Geometry(geom)
  if polygons.type == 'Polygon':
      return polygons
  elif polygons.type == 'MultiPolygon':
      largest = max(polygons.shapely, key=lambda polygon: polygon.area)
      return Geometry.from_shapely(largest)
  else:
      return None
$$ LANGUAGE plpythonu;