Get all "someValuesFrom" of an object property class with Jena - jena

Question

I want to get all the values of "someValuesFrom" of each Object Property as a list.
I have this part of an owl file:
<owl:Class rdf:about="http://www.semanticweb.org/gumaro/ontologies/2017/11/untitled-ontology-26#ErgativeFrame">
<owl:equivalentClass>
<owl:Restriction>
<owl:onProperty rdf:resource="http://www.semanticweb.org/gumaro/ontologies/2017/11/untitled-ontology-26#hasAgent"/>
<owl:someValuesFrom>
<owl:Class>
<owl:unionOf rdf:parseType="Collection">
<rdf:Description rdf:about="http://www.semanticweb.org/gumaro/ontologies/2017/11/untitled-ontology-26#Animal"/>
<rdf:Description rdf:about="http://www.semanticweb.org/gumaro/ontologies/2017/11/untitled-ontology-26#Object"/>
<rdf:Description rdf:about="http://www.semanticweb.org/gumaro/ontologies/2017/11/untitled-ontology-26#Person"/>
</owl:unionOf>
</owl:Class>
</owl:someValuesFrom>
</owl:Restriction>
</owl:equivalentClass>
<owl:equivalentClass>
<owl:Restriction>
<owl:onProperty rdf:resource="http://www.semanticweb.org/gumaro/ontologies/2017/11/untitled-ontology-26#hasMainAction"/>
<owl:someValuesFrom rdf:resource="http://www.semanticweb.org/gumaro/ontologies/2017/11/untitled-ontology-26#ErgativeVerb"/>
</owl:Restriction>
</owl:equivalentClass>
<owl:equivalentClass>
<owl:Restriction>
<owl:onProperty rdf:resource="http://www.semanticweb.org/gumaro/ontologies/2017/11/untitled-ontology-26#hasOptionalPatient"/>
<owl:someValuesFrom>
<owl:Class>
<owl:unionOf rdf:parseType="Collection">
<rdf:Description rdf:about="http://www.semanticweb.org/gumaro/ontologies/2017/11/untitled-ontology-26#Animal"/>
<rdf:Description rdf:about="http://www.semanticweb.org/gumaro/ontologies/2017/11/untitled-ontology-26#Beverage"/>
<rdf:Description rdf:about="http://www.semanticweb.org/gumaro/ontologies/2017/11/untitled-ontology-26#BodyPart"/>
<rdf:Description rdf:about="http://www.semanticweb.org/gumaro/ontologies/2017/11/untitled-ontology-26#ClosedLocation"/>
<rdf:Description rdf:about="http://www.semanticweb.org/gumaro/ontologies/2017/11/untitled-ontology-26#Clothing"/>
<rdf:Description rdf:about="http://www.semanticweb.org/gumaro/ontologies/2017/11/untitled-ontology-26#Food"/>
<rdf:Description rdf:about="http://www.semanticweb.org/gumaro/ontologies/2017/11/untitled-ontology-26#Furniture"/>
<rdf:Description rdf:about="http://www.semanticweb.org/gumaro/ontologies/2017/11/untitled-ontology-26#NatureElement"/>
<rdf:Description rdf:about="http://www.semanticweb.org/gumaro/ontologies/2017/11/untitled-ontology-26#NaturePhenomenon"/>
<rdf:Description rdf:about="http://www.semanticweb.org/gumaro/ontologies/2017/11/untitled-ontology-26#OpenLocation"/>
<rdf:Description rdf:about="http://www.semanticweb.org/gumaro/ontologies/2017/11/untitled-ontology-26#Person"/>
<rdf:Description rdf:about="http://www.semanticweb.org/gumaro/ontologies/2017/11/untitled-ontology-26#Toy"/>
<rdf:Description rdf:about="http://www.semanticweb.org/gumaro/ontologies/2017/11/untitled-ontology-26#Transport"/>
<rdf:Description rdf:about="http://www.semanticweb.org/gumaro/ontologies/2017/11/untitled-ontology-26#Vegetal"/>
</owl:unionOf>
</owl:Class>
</owl:someValuesFrom>
</owl:Restriction>
</owl:equivalentClass>
<rdfs:subClassOf rdf:resource="http://www.semanticweb.org/gumaro/ontologies/2017/11/untitled-ontology-26#Frame"/>
</owl:Class>
I've tried something like this:
OntClass ontClass = this.ontModel.getOntClass(NS_OWL + "ErgativeFrame");
List<OntClass> list = ontClass.listEquivalentClasses().toList();
for (OntClass equiv: list) {
if (equiv.isRestriction()) {
System.out.println("is restriction");
System.out.println(equiv.getLocalName());
}
}
The quantity of "is restriction" printed on the screen is equal to the length of properties, but getLocalName is always "null".
What do I have to do?
EDIT: I've got the name of property correctly doing some changes in the code (see below).
Now I still can't get the "someValueFrom".
OntClass ontClass = this.ontModel.getOntClass(NS_OWL + "ErgativeFrame");
List<OntClass> list = ontClass.listEquivalentClasses().toList();
for (OntClass equiv: list) {
if (equiv.isRestriction()) {
System.out.println("is restriction");
System.out.println(equiv.asRestriction().getOnProperty().getLocalName());
}
}

Answer 1

The reason why getLocalName is returning null is because you are using anonymous classes and properties, i.e. classes and properties without assigned URIs. Since Jena cannot find the URI, it returns null.
To illustrate, here is a subset of your ontology with named classes and properties rather than anonymous classes and properties:
<rdf:Description rdf:about="http://www.w3.org/2002/07/owl#topObjectProperty">
<rdfs:range rdf:resource="http://www.semanticweb.org/gumaro/ontologies/2017/11/untitled-ontology-26#AnimalObjectPerson"/>
</rdf:Description>
<owl:Class rdf:about="http://www.semanticweb.org/gumaro/ontologies/2017/11/untitled-ontology-26#Frame"/>
<owl:Class rdf:about="http://www.semanticweb.org/gumaro/ontologies/2017/11/untitled-ontology-26#Object"/>
<owl:Class rdf:about="http://www.semanticweb.org/gumaro/ontologies/2017/11/untitled-ontology-26#Person"/>
<owl:Class rdf:about="http://www.semanticweb.org/gumaro/ontologies/2017/11/untitled-ontology-26#Animal"/>
<owl:Class rdf:about="http://www.semanticweb.org/gumaro/ontologies/2017/11/untitled-ontology-26#AnimalObjectPerson">
<owl:equivalentClass>
<owl:Class>
<owl:unionOf rdf:parseType="Collection">
<rdf:Description rdf:about="http://www.semanticweb.org/gumaro/ontologies/2017/11/untitled-ontology-26#Animal"/>
<rdf:Description rdf:about="http://www.semanticweb.org/gumaro/ontologies/2017/11/untitled-ontology-26#Object"/>
<rdf:Description rdf:about="http://www.semanticweb.org/gumaro/ontologies/2017/11/untitled-ontology-26#Person"/>
</owl:unionOf>
</owl:Class>
</owl:equivalentClass>
</owl:Class>
<owl:Class rdf:about="http://www.semanticweb.org/gumaro/ontologies/2017/11/untitled-ontology-26#ErgativeFrame">
<owl:equivalentClass>
<owl:Restriction>
<owl:onProperty rdf:resource="http://www.semanticweb.org/gumaro/ontologies/2017/11/untitled-ontology-26#hasAgent"/>
<owl:someValuesFrom rdf:resource="http://www.w3.org/2002/07/owl#Thing"/>
</owl:Restriction>
</owl:equivalentClass>
<rdfs:subClassOf rdf:resource="http://www.semanticweb.org/gumaro/ontologies/2017/11/untitled-ontology-26#Frame"/>
</owl:Class>
and here is the code for retrieving the range of the property:
OntClass ontClass = ontModel.getOntClass(NS_OWL + "ErgativeFrame");
List<OntClass> list = ontClass.listEquivalentClasses().toList();
for (OntClass equiv: list) {
if (equiv.isRestriction()) {
OntProperty ontProperty = equiv.asRestriction().getOnProperty();
OntResource range = ontProperty.getRange();
List<OntClass> rangeList = range.asClass().listEquivalentClasses().toList();
for (OntClass rangeEquiv: rangeList) {;
for (OntClass rangeUnionClass: rangeEquiv.asUnionClass().listOperands().toList()) {
System.out.println("classes in union = " + rangeUnionClass);
}
}
}
}
I hope that helps.

Answer 2

In the provided snippet there is ambiguous situation: the restriction ...#hasMainAction + ...#ErgativeVerb could be either Data or Object Property Existential Quantification Restriction (for more about this see owl2 guide).
There are no explicit declarations in the snippet to judge what it is exaclty.
All Restrictions are anonymous resources (class expressions) - that's why they have no uri and local name therefore.
Jena-API (the package org.apache.jena.ontology) is only for outdated OWL-1, not OWL-2.
But there is a jena-based analogue of org.apache.jena.ontology.OntModel - special for OWL-2: com.github.owlcs.ontapi.jena.model.OntModel.
Although it is not directly related to the original question, it might be more useful in this case.
Here is an example:
String fullOwlAsString = "<?xml version=\"1.0\" encoding=\"utf-8\"?>\n" +
"<rdf:RDF xmlns=\"http://www.semanticweb.org/owlapi/test#\"\n" +
" xml:base=\"http://www.semanticweb.org/owlapi/test\"\n" +
" xmlns:xsd=\"http://www.w3.org/2001/XMLSchema#\"\n" +
" xmlns:rdfs=\"http://www.w3.org/2000/01/rdf-schema#\"\n" +
" xmlns:rdf=\"http://www.w3.org/1999/02/22-rdf-syntax-ns#\"\n" +
" xmlns:owl=\"http://www.w3.org/2002/07/owl#\">" +
"<owl:Ontology rdf:about=\"#\" />" + yourSnippet + "</rdf:RDF>";
InputStream in = new ByteArrayInputStream(fullOwlAsString.getBytes(StandardCharsets.UTF_8));
OntModel ont = OntManagers.createONT().loadOntologyFromOntologyDocument(in).asGraphModel();
ont.ontObjects(OntClass.ObjectSomeValuesFrom.class).map(x -> x.getValue())
.filter(x -> x.canAs(OntClass.ComponentsCE.class))
.map(x -> (OntClass.ComponentsCE<? extends OntObject>)x.as(OntClass.ComponentsCE.class))
.flatMap(x -> x.getList().members())
.filter(RDFNode::isResource).map(RDFNode::asResource).map(Resource::getLocalName)
.forEach(System.out::println);
And the output:
Animal
Beverage
BodyPart
ClosedLocation
Clothing
Food
Furniture
NatureElement
NaturePhenomenon
OpenLocation
Person
Toy
Transport
Vegetal
Animal
Object
Person