Add support for GeoSPARQL

[ch-sander]

A boolean for falls within and contains based in the specifications (e.g. http://www.opengis.net/def/function/geosparql/sfWithin). Either done within sqlite or with GeoPandas/Shapely/Fiona

[ch-sander]

Will come with the latest oxigraph built

[ch-sander]

using custom_functions in query params {px.NamedNode("http://shmarql.com/geo/distance"): distance_function_wkt}

def distance_function_wkt(t1, t2):
    try:
        point1 = wkt.loads(t1.value)
        point2 = wkt.loads(t2.value)
        coords1 = (point1.y, point1.x)
        coords2 = (point2.y, point2.x)
        distance_km = geodesic(coords1, coords2).kilometers
        return Literal(str(distance_km))
    except Exception as e:
        return Literal("-1")

@Tpt thanks for the suggestions. I wonder how to return a numerical literal. Moreover, the Exception handling probably is idiotic...

Yet, this works as a start:

PREFIX rdf: <http://www.w3.org/1999/02/22-rdf-syntax-ns#>
PREFIX geo: <http://shmarql.com/geo/>

SELECT DISTINCT 
  ?event_1 
  ?event_1_label 
  ?map_8 
  ?map_6 
  ?distance
WHERE {
  ?event_1 rdf:type <http://www.graceful17.org/ontology/event>;
           <http://www.graceful17.org/ontology/called> ?event_1_label;
           <http://www.graceful17.org/ontology/place_of_event> ?place_2.
           
  ?place_2 rdf:type <http://www.graceful17.org/ontology/place>;
           <http://www.graceful17.org/ontology/wkt> ?map_6.
           
  ?event_1 (<http://www.graceful17.org/ontology/event_related_to_object>/<http://www.graceful17.org/ontology/in_diocese>/<http://www.graceful17.org/ontology/primary_place>) ?place_4.
  
  ?place_4 rdf:type <http://www.graceful17.org/ontology/place>;
           <http://www.graceful17.org/ontology/wkt> ?map_8.
         BIND(geo:distance(?map_6, ?map_8) AS ?distance)
  

}
LIMIT 10000

It shows job applications for new positions, and the distance between the place of the job and the place where the application is decided on...

[Tpt]

@Tpt thanks for the suggestions. I wonder how to return a numerical literal.

Just set a datatype:

return Literal(str(distance_km), datatype=NamedNode('http://www.w3.org/2001/XMLSchema#integer'))

It would be great that I update Literal constructor to allow various Python types as input (int, float, bool, datetime...)

Moreover, the Exception handling probably is idiotic...

You can return None to make the function fail and the result row ignored. Or just not catch the exception. In this case, the exception will be catched by oxigraph and the row ignored too.

[ch-sander]

Great, thanks @Tpt

It would be great that I update Literal constructor to allow various Python types as input (int, float, bool, datetime...)

yes, that would be even better. Even without aggregation, there are still quite useful applications, I have implemented geo/area as well as logarithm (#26 ) and Levenshtein distance. I will think of more, like making a convex hull of geometries, getting centroids, etc.