merlinr68 / geosparql-geojson

An implementation of GeoSPARQL's Simple Features SPARQL functions for GeoJSON geometries, as per GeoSPARQL

RDFLib GeoSPARQ functions for GeoJSON

This library provides support for the GeoSPARQL 1.1 Simple Features Relation Family for geometries expressed as GeoJSON Literals. It has drawn heavily on geosparql-dggs (https://github.com/RDFLib/geosparql-dggs).

Installation

!pip install rdflib
!pip install git+https://github.com/inova8/geosparql-geojson.git

This package depends on to support the functions' use against graphs RDFlib. The functions depend on the shapely library

Use

from rdflib import Literal, Graph, Namespace, URIRef
from rdflib.namespace import GEO
import geojson
imprt json

g = Graph()
g.add((URIRef('https://geom-a'), GEO.hasGeometry, Literal('''{"coordinates":[[[ 0,1],[4,1],[4,5],[0,5],[0,1]]],"type": "Polygon"}''',datatype=GEO.geoJSONLiteral)))
g.add((URIRef('https://geom-b'), GEO.hasGeometry, Literal(json.loads('''{"coordinates": [[[ 0,1],[2,1],[2,3],[0,3],[0,1]]],"type": "Polygon"}'''))))
g.add((URIRef('https://geom-c'), GEO.hasGeometry, Literal(json.loads('''{"coordinates": [[[ 4,3],[6,3],[6,5],[4,5],[4,3]]],"type": "Polygon"}'''),datatype=GEO.geoJSONLiteral)))
g.add((URIRef('https://geom-e'), GEO.hasGeometry, Literal('''{"coordinates": [[2,0],[3,3]],"type": "LineString"}''')))
g.add((URIRef('https://geom-f'), GEO.hasGeometry, Literal('''{"coordinates": [ 2,4],"type": "Point"}''')))

Note that the literal value for the GEO.hasGeometry can be any of the following

• string of json
• typed datatype=GEO.geoJSONLiteral or untyped

We can now query the graph g, invoking geojson functions as follows:

# Query the in-memory graph
q = """
    PREFIX geo: <http://www.opengis.net/ont/geosparql#>

    SELECT ?a ?b
    WHERE {
        ?a geo:hasGeometry ?a_geom .
        ?b geo:hasGeometry ?b_geom .

        FILTER geo:sfWithin(?a_geom, ?b_geom)
    }"""
# Interate through and print results
for r in g.query(q):
  print(f"{r['a']} is within {r['b']}")

The results should be:

https://geom-a is within https://geom-a
https://geom-b is within https://geom-a
https://geom-b is within https://geom-b
https://geom-c is within https://geom-c
https://geom-f is within https://geom-a
https://geom-f is within https://geom-f

The geojson functions can also be used directly with RDFLib as follows:

geojson.contains(Literal('''{"coordinates":[[[ 0,1],[4,1],[4,5],[0,5],[0,1]]],"type": "Polygon"}'''),
                 Literal('''{"coordinates": [ 2,4],"type": "Point"}''')).value

which returns

True

Function Definitions

• geo:sfEqual: Returns Literal(true) if the first geometry is equal to the second geometry.
• geo:sfWithin: Returns Literal(true) if the first geometry is within the second geometry.
• geo:sfContains: Returns Literal(true) if the first geometry contains the second geometry.
• geo:sfIntersects: Returns Literal(true) if the first geometry intersects (i.e. has any spatial relation other than disjoint) the second geometry.
• geo:sfTouches: Returns Literal(true) if the first geometry touches the second geometry.
• geo:sfDisjoint: Returns Literal(true) if the first geometry is disjoint with the second geometry.
• geo:sfOverlaps: Returns Literal(true) if the first geometry overlaps the second geometry.

Testing

All tests are in tests/ and implemented using pytest.

Contributing

Via GitHub, Issues & Pull Requests:

https://github.com/Inova8/geosparql-geojson

License

This code is licensed with the BSD 3-clause license as per LICENSE which is the same license as used for rdflib.

Citation

@software{https://github.com/Inova8/geosparql-geojson, author = {{Peter lawrence}}, title = {RDFlib GeoSPARQL Functions for GeoJSON}, version = {0.1.0}, date = {2024}, url = {https://github.com/Inova8/geosparql-geojson} } Contact Creator & maintainer: Peter Lawrence Application Architect inova8 plc [email protected]