Problems with st_distance

[Frederik Janssen]

We have a query that certainly has worked some time ago but now does not work any more:

Prefix geo: <http://geovocab.org/geometry#>
Prefix lgdo: <http://linkedgeodata.org/ontology/>
Prefix rdfs: <http://www.w3.org/2000/01/rdf-schema#>
Prefix rdf: <http://www.w3.org/1999/02/22-rdf-syntax-ns#>
Prefix ogc: <http://www.opengis.net/ont/geosparql#>

Select ?node ?label ?type ?location  (<bif:st_distance> (?location,
<bif:st_point> (8.00863593515,49.9771504215)) as ?distance) FROM
<http://linkedgeodata.org>  {
     ?node rdfs:label ?label .
     ?node rdf:type ?type .
     ?node geo:geometry [ogc:asWKT ?location] .
     Filter(<bif:st_intersects> (?location, <bif:st_point>
(8.00863593515,49.9771504215), 2.0)) .
FILTER (contains(str(?type),"linkedgeodata.org/onto"))} ORDER BY DESC(?node)

The purpose is to yield all locations inside a radius of 2km around the given point.

The error is:
Virtuoso 22023 Error GEO..: Function st_distance() expects a geometry of  type 1 as argument 0, not geometry of type 2

Any ideas?

Thanks
Frederik

[Irene Celino]

Curious, I encountered the same issue yesterday :-)

If I got it correctly, the problem is that st_distance works only with points and in your query you are not checking that ?node is a lgdm:Node and not a lgdm:Way.

Try adding the following filter:
FILTER NOT EXISTS { ?node a lgdm:Way. }

I'd be happy if some Virtuoso expert could confirm/refute or give a better explanation.

HTH,

Irene

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[Hugh Williams]

Hi Fredrick,

The query contain "<bif:st_distance>" with no params being passed to the st_distance() function which needs in put params hence the error, see documentation at:

http://virtuoso.openlinksw.com/dataspace/doc/dav/wiki/Main/VirtGeoSPARQLEnhancementDocs#Virtuoso Geo Spatial geometry functions

Best Regards

Hugh Williams

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