non-owl class in DBpedia.owl loaded as superclass, causing 'cannot convert node to OntClass: it does not have rdf:type owl:Class or equivalent'

Mon, 01 Aug 2016 03:56:56 -0700 

Hi
I am processing DBpedia.owl (http://downloads.dbpedia.org/2015-10/dbpedia_2015-10.owl) to read every class and their superclasses. The java code is as below: 

>>>
OntModel base = ModelFactory.createOntologyModel(OntModelSpec.OWL_MEM);
OntModel model= (OntModel) base.read(ontURL);
ExtendedIterator<OntClass> it = model.listNamedClasses();


while (it.hasNext()) { OntClass c = it.next(); 
ExtendedIterator<OntClass> it = c.listSuperClasses(false); 
while(it.hasNext()){ //LINE A OntClass sc = it.next(); ... } }



<<< When the OntClass correspond to the one defined below: >>>     
<owl:Class rdf:about="http://dbpedia.org/ontology/Weapon";>             
<rdfs:label xml:lang="en">weapon</rdfs:label>             
<rdfs:subClassOf rdf:resource="http://dbpedia.org/ontology/Device"/> 
            <rdfs:subClassOf rdf:resource="http://schema.org/Product"/> 
            <owl:equivalentClass 
rdf:resource="http://www.wikidata.org/entity/Q728"/><prov:wasDerivedFrom 
rdf:resource="http://mappings.dbpedia.org/index.php/OntologyClass:Weapon"/> 
    </owl:Class> <<< Line A causes an exception. >>> 
org.apache.jena.ontology.ConversionException: Cannot convert node 
http://schema.org/Product to OntClass: it does not have rdf:type 
owl:Class or equivalent     at 
org.apache.jena.ontology.impl.OntClassImpl$1.wrap(OntClassImpl.java:82) 
    at org.apache.jena.enhanced.EnhNode.convertTo(EnhNode.java:152)     
at org.apache.jena.enhanced.EnhNode.convertTo(EnhNode.java:31)     at 
org.apache.jena.enhanced.Polymorphic.asInternal(Polymorphic.java:62)     
at org.apache.jena.enhanced.EnhNode.as(EnhNode.java:107)     at 
org.apache.jena.ontology.impl.OntResourceImpl.lambda$listDirectPropertyValues$30(OntResourceImpl.java:1536) 
    at 
org.apache.jena.util.iterator.Map1Iterator.next(Map1Iterator.java:46) 
    at 
org.apache.jena.util.iterator.WrappedIterator.next(WrappedIterator.java:94) 
    at 
org.apache.jena.util.iterator.FilterIterator.hasNext(FilterIterator.java:56) 
    at 
org.apache.jena.util.iterator.WrappedIterator.hasNext(WrappedIterator.java:90) 
    at 
org.apache.jena.util.iterator.FilterIterator.hasNext(FilterIterator.java:55) 
    at 
org.apache.jena.util.iterator.WrappedIterator.hasNext(WrappedIterator.java:90) 
    at 
org.apache.jena.util.iterator.FilterIterator.hasNext(FilterIterator.java:55) 
<<< I think the problem is that 'http://schema.org/Product' refers to a 
class defined in another resource. And this class is not defined in this 
owl file. How can this be addressed please? Thanks!





















					Reply via email to