Singapore Data.

[ankit solanki]

Hello Folks, 

I am new to the world of Linked Open Data. 

I have been trying to understand the whole Sparql concept by learning through examples. In due process I observed that the data from Singapore is quite less. Is it something that you guys also observed or am I wrong somewhere.

Query:

PREFIX lgdo:<http://linkedgeodata.org/ontology/> 

PREFIX rdfs: <http://www.w3.org/2000/01/rdf-schema#> 

SELECT * 

FROM <http://linkedgeodata.org> 

WHERE 

{

   ?b <http://www.w3.org/1999/02/22-rdf-syntax-ns#type> <http://linkedgeodata.org/ontology/Attraction>.

optional{

?b <http://www.w3.org/2000/01/rdf-schema#label> ?a.

} 

OPTIONAL {

    ?b <http://linkedgeodata.org/ontology/is_in%3Acountry> ?c .

    }

FILTER ( ?c = "Singapore" )

}

LIMIT 100000 

Thanks! 

Ankit Solanki 

[Claus Stadler]

Hi Ankit,

A thing in advance: Result sets are currently limited to 2000 results, so LIMIT 100000 won't return that much.


Unfortunately it seems that the OSM data is very incomplete for Singapore:
Running the following simplified query on the virtual Sparql endpoint (which rewrites the query to a complete OSM database) at http://linkedgeodata.org/vsnorql,
only yields 3 results:

PREFIX lgdo:<http://linkedgeodata.org/ontology/>
PREFIX rdfs: <http://www.w3.org/2000/01/rdf-schema#>

SELECT *
FROM <http://linkedgeodata.org>
WHERE
{

?b <http://linkedgeodata.org/ontology/is_in%3Acountry> ?c .
Filter(str(?c) = "Singapore")
}



Fortunately you can do a bounding box query:
I quickly derived a bounding box from the GADM (http://gadm.org) polygon for Signapore.
I am locally experimenting in integrating this dataset with LinkedGeoData; but first have to ask the people there whether it would be ok to 'redistribute' parts of their data via SPARQL.
Here is your query:

Note that this currently only works on http://linkedgeodata.org/vsnorql (and http://linkedgeodata.org/vsparql)
but NOT on http://linkedgeodata.org/sparql

Prefix rdfs: <http://www.w3.org/2000/01/rdf-schema#>
Prefix ogc: <http://www.opengis.net/ont/geosparql#>
Prefix geom: <http://geovocab.org/geometry#>
Prefix lgdo: <http://linkedgeodata.org/ontology/>

Select *
{
?s
geom:geometry [
ogc:asWKT ?g
] .

Filter(bif:st_intersects(?g, bif:st_geomFromText('POLYGON((103.616668701172 1.16638994216925,103.616668701172 1.47138798236875,104.085800170899 1.47138798236875,104.085800170899 1.16638994216925,103.616668701172 1.16638994216925))')))
}

Cheers,
Claus

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--
Dipl. Inf. Claus Stadler
Department of Computer Science, University of Leipzig
Research Group: http://aksw.org/
Workpage & WebID: http://aksw.org/ClausStadler
Phone: +49 341 97-32260