I am have a reference to an object of type com.hp.hpl.jena.rdf.model.Resource that is contained in a Bag. I want to list all the Bags that contain this resource. Is there a function similar to listResourcesWithProperty that can be used to search for the containers. ´
The Bag has no properties added. It only has a collection of resources added using Bag.add(RDFNode o)
This is actually a bit tricky if you don't have inference available because a number of properties are actually used to indicate RDF container membership. E.g., here's a model with three bags, the first and third of which both contain resouces x and y:
@prefix : <http://stackoverflow.com/q/23568540/1281433/> .
@prefix rdf: <http://www.w3.org/1999/02/22-rdf-syntax-ns#> .
:Bag1 a rdf:Bag ;
rdf:_1 :x ;
rdf:_2 :y .
:Bag2 a rdf:Bag ;
rdf:_1 :y .
:Bag3 a rdf:Bag ;
rdf:_1 :y ;
rdf:_2 :x .
The problem, of course, is that the properties that the first and third bag to, e.g., the resource x are not the same. However, each of those rdf:_nnn properties is an instance of rdfs:ContainerMembershipProperty. In turn, each rdfs:ContainerMembershipProperty is a superproperty of rdfs:member. This means that if you have a reasoner that can infer that, you can ask what resources have x (or y) as an rdfs:member. It doesn't seem (as shown by the following example) that Jena's RDFS reasoners do this. As such, you might just have to iterate over statements that have x as an object, and check whether the property is a container membership property.
import org.apache.jena.riot.Lang;
import org.apache.jena.riot.RDFDataMgr;
import com.hp.hpl.jena.ontology.OntModel;
import com.hp.hpl.jena.ontology.OntModelSpec;
import com.hp.hpl.jena.rdf.model.Bag;
import com.hp.hpl.jena.rdf.model.Model;
import com.hp.hpl.jena.rdf.model.ModelFactory;
import com.hp.hpl.jena.rdf.model.ResIterator;
import com.hp.hpl.jena.rdf.model.Resource;
import com.hp.hpl.jena.rdf.model.Statement;
import com.hp.hpl.jena.rdf.model.StmtIterator;
import com.hp.hpl.jena.vocabulary.RDF;
import com.hp.hpl.jena.vocabulary.RDFS;
public class BagExample {
public static void main(String[] args) {
Model model = ModelFactory.createDefaultModel();
String NS = "http://stackoverflow.com/q/23568540/1281433/";
model.setNsPrefix( "", NS );
model.setNsPrefix( "rdf", RDF.getURI() );
Bag bag1 = model.createBag( NS+"Bag1" );
Bag bag2 = model.createBag( NS+"Bag2" );
Bag bag3 = model.createBag( NS+"Bag3" );
Resource x = model.createResource( NS+"x" );
Resource y = model.createResource( NS+"y" );
bag1.add( x ).add( y );
bag2.add( y );
bag3.add( y ).add( x );
RDFDataMgr.write( System.out, model, Lang.TURTLE );
System.out.println( "=== Bags with X (no inference) ===" );
ResIterator bagsWithX = model.listSubjectsWithProperty( RDFS.member, x );
while ( bagsWithX.hasNext() ) {
System.out.println( bagsWithX.next() );
}
System.out.println( "=== Bags with X (RDFS inference) ===" );
OntModel rdfsModel = ModelFactory.createOntologyModel( OntModelSpec.RDFS_MEM_TRANS_INF, model );
bagsWithX = rdfsModel.listSubjectsWithProperty( RDFS.member, x );
while ( bagsWithX.hasNext() ) {
System.out.println( bagsWithX.next() );
}
System.out.println( "=== Bags with X (manual checking) ===" );
StmtIterator xStmts = model.listStatements( null, null, x );
while ( xStmts.hasNext() ) {
Statement s = xStmts.next();
// This checks whether the URI begins with rdf:_. A proper
// solution would make sure that the suffix is actually numeric.
// You might also want to check whether the subject actually is
// a Bag. It could be a member of other kinds of containers, too.
if ( s.getPredicate().getURI().startsWith( RDF.getURI()+"_" ) ) {
System.out.println( s.getObject() );
}
}
}
}
=== Bags with X (no inference) ===
=== Bags with X (RDFS inference) ===
=== Bags with X (manual checking) ===
http://stackoverflow.com/q/23568540/1281433/x
http://stackoverflow.com/q/23568540/1281433/x