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Posted to users@jena.apache.org by Alex To <to...@gmail.com> on 2019/09/05 01:11:11 UTC
How to use ontModel.listHierarchyRootClasses() properly
Hi I am trying to load schema.org ontology and get all top classes
using ontModel.listHierarchyRootClasses() but can't get the expected
results with different OntModelSpec.
If I use OWL_MEM, it lists 2500+ records with all the records have "null"
URI.
If I use OWL_DL_MEM, it lists 0 records
The code is very simple as follows
Model model = ModelFactory.createDefaultModel();
model.read("https://schema.org/docs/schemaorg.owl");
OntModel ontModel =
ModelFactory.createOntologyModel(OntModelSpec.OWL_MEM, model);
ExtendedIterator<OntClass> topClazzez = ontModel.listHierarchyRootClasses();
while (topClazzez.hasNext()) {
OntClass clazz = topClazzez.next();
System.out.println(clazz.getURI());
}
A minimal Maven project ready to run to demonstrate my problem is here
https://github.com/AlexTo/jena-lab (have a look at the Main.java)
Thanks a lot
--
Alex To
PhD Candidate
School of Computer Science
Knowledge Discovery and Management Research Group
Faculty of Engineering & IT
THE UNIVERSITY OF SYDNEY | NSW | 2006
Desk 4e69 | Building J12| 1 Cleveland Street
M. +61423330656 <%2B61450061602>
Re: How to use ontModel.listHierarchyRootClasses() properly
Posted by Alex To <to...@gmail.com>.
Hi Lorenz
Thanks a lot, your SPARQL seems to be more accurate, I see more top classes
including schema:DataType
Have a nice weekend
On Fri, Sep 6, 2019 at 4:25 PM Lorenz Buehmann <
buehmann@informatik.uni-leipzig.de> wrote:
>
> yes SPARQL is indeed possible. But in that case, I'd go the SPARQL 1.1 way:
>
> |SELECT DISTINCT ?s||
> ||WHERE||
> || { ?s a owl:Class||
> || FILTER ( ! isBlank(?s) )||
> || FILTER ( ?s NOT IN (owl:Thing, owl:Nothing) )||
> || FILTER NOT EXISTS { ?s rdfs:subClassOf ?super||
> || FILTER ( ( ?super NOT IN (rdfs:Resource,
> owl:Thing, rdfs:Class) ) && ( ?s != ?super ) )||
> || }||
> || }|
>
>
> On 06.09.19 03:47, Alex To wrote:
> > Thanks Lorenz
> >
> > I figured out the union thing too so I ended up using the below SPARQL
> > instead and it seems to work fine but would love to know what is the
> > equivalent using Jena API
> >
> > "SELECT DISTINCT ?s WHERE { " +
> > "?s a owl:Class . " +
> > "FILTER (!isBlank(?s)) " +
> > "FILTER (?s != owl:Thing && ?s != owl:Nothing) . " +
> > "OPTIONAL { " +
> > " ?s rdfs:subClassOf ?super . " +
> > " FILTER (?super != rdfs:Resource && ?super != owl:Thing
> > && ?s != ?super) " +
> > " } . " +
> > "FILTER (!bound(?super))" +
> > "}");
> >
> >
> > Regards
> >
> >
> > On Thu, Sep 5, 2019 at 8:00 PM Lorenz Buehmann <
> > buehmann@informatik.uni-leipzig.de> wrote:
> >
> >> schema.org contains a bunch of anonymous classes like the union of
> other
> >> classes which are used as domain or range of a property, that's why you
> >> get null values because they do not have a URI. If you'd just call
> >>
> >> |System.out.println(clazz);|
> >>
> >>
> >> you'd see the blank node Ids.
> >>
> >>
> >> Among all those blank nodes, there is indeed the one top level class
> >> http://schema.org/Thing .
> >>
> >>
> >> I thought just adding a filter on the iterator is enough, i.e.
> >>
> >> |topClazzez = topClazzez.filterDrop(OntResource::isAnon);|
> >>
> >>
> >> but while it doesn't return the blank nodes anymore, it leads to an
> >> exception:
> >>
> >>
> >> |Exception in thread "main"
> >> org.apache.jena.ontology.ConversionException: Cannot convert node
> >> http://www.w3.org/2000/01/rdf-schema#Class 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$8(OntResourceImpl.java:1536)||
> >> || at
> >> org.apache.jena.util.iterator.Map1Iterator.next(Map1Iterator.java:46)||
> >> || at
> >>
> >>
> org.apache.jena.ontology.impl.OntResourceImpl.computeDirectValues(OntResourceImpl.java:1580)||
> >> || at
> >>
> >>
> org.apache.jena.ontology.impl.OntResourceImpl.listDirectPropertyValues(OntResourceImpl.java:1553)||
> >> || at
> >>
> >>
> org.apache.jena.ontology.impl.OntClassImpl.listSuperClasses(OntClassImpl.java:180)||
> >> || at
> >>
> >>
> org.apache.jena.ontology.impl.OntClassImpl.isHierarchyRoot(OntClassImpl.java:739)||
> >> || 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 com.company.Main.main(Main.java:25)|
> >>
> >>
> >>
> >> On 05.09.19 03:11, Alex To wrote:
> >>> Hi I am trying to load schema.org ontology and get all top classes
> >>> using ontModel.listHierarchyRootClasses() but can't get the expected
> >>> results with different OntModelSpec.
> >>>
> >>> If I use OWL_MEM, it lists 2500+ records with all the records have
> "null"
> >>> URI.
> >>> If I use OWL_DL_MEM, it lists 0 records
> >>>
> >>> The code is very simple as follows
> >>>
> >>> Model model = ModelFactory.createDefaultModel();
> >>> model.read("https://schema.org/docs/schemaorg.owl");
> >>> OntModel ontModel =
> >>> ModelFactory.createOntologyModel(OntModelSpec.OWL_MEM, model);
> >>> ExtendedIterator<OntClass> topClazzez =
> >> ontModel.listHierarchyRootClasses();
> >>> while (topClazzez.hasNext()) {
> >>> OntClass clazz = topClazzez.next();
> >>> System.out.println(clazz.getURI());
> >>> }
> >>>
> >>> A minimal Maven project ready to run to demonstrate my problem is here
> >>> https://github.com/AlexTo/jena-lab (have a look at the Main.java)
> >>>
> >>> Thanks a lot
> >
> > --
> >
>
--
Alex To
PhD Candidate
School of Computer Science
Knowledge Discovery and Management Research Group
Faculty of Engineering & IT
THE UNIVERSITY OF SYDNEY | NSW | 2006
Desk 4e69 | Building J12| 1 Cleveland Street
M. +61423330656 <%2B61450061602>
Re: How to use ontModel.listHierarchyRootClasses() properly
Posted by Lorenz Buehmann <bu...@informatik.uni-leipzig.de>.
yes SPARQL is indeed possible. But in that case, I'd go the SPARQL 1.1 way:
|SELECT DISTINCT ?s||
||WHERE||
|| { ?s a owl:Class||
|| FILTER ( ! isBlank(?s) )||
|| FILTER ( ?s NOT IN (owl:Thing, owl:Nothing) )||
|| FILTER NOT EXISTS { ?s rdfs:subClassOf ?super||
|| FILTER ( ( ?super NOT IN (rdfs:Resource,
owl:Thing, rdfs:Class) ) && ( ?s != ?super ) )||
|| }||
|| }|
On 06.09.19 03:47, Alex To wrote:
> Thanks Lorenz
>
> I figured out the union thing too so I ended up using the below SPARQL
> instead and it seems to work fine but would love to know what is the
> equivalent using Jena API
>
> "SELECT DISTINCT ?s WHERE { " +
> "?s a owl:Class . " +
> "FILTER (!isBlank(?s)) " +
> "FILTER (?s != owl:Thing && ?s != owl:Nothing) . " +
> "OPTIONAL { " +
> " ?s rdfs:subClassOf ?super . " +
> " FILTER (?super != rdfs:Resource && ?super != owl:Thing
> && ?s != ?super) " +
> " } . " +
> "FILTER (!bound(?super))" +
> "}");
>
>
> Regards
>
>
> On Thu, Sep 5, 2019 at 8:00 PM Lorenz Buehmann <
> buehmann@informatik.uni-leipzig.de> wrote:
>
>> schema.org contains a bunch of anonymous classes like the union of other
>> classes which are used as domain or range of a property, that's why you
>> get null values because they do not have a URI. If you'd just call
>>
>> |System.out.println(clazz);|
>>
>>
>> you'd see the blank node Ids.
>>
>>
>> Among all those blank nodes, there is indeed the one top level class
>> http://schema.org/Thing .
>>
>>
>> I thought just adding a filter on the iterator is enough, i.e.
>>
>> |topClazzez = topClazzez.filterDrop(OntResource::isAnon);|
>>
>>
>> but while it doesn't return the blank nodes anymore, it leads to an
>> exception:
>>
>>
>> |Exception in thread "main"
>> org.apache.jena.ontology.ConversionException: Cannot convert node
>> http://www.w3.org/2000/01/rdf-schema#Class 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$8(OntResourceImpl.java:1536)||
>> || at
>> org.apache.jena.util.iterator.Map1Iterator.next(Map1Iterator.java:46)||
>> || at
>>
>> org.apache.jena.ontology.impl.OntResourceImpl.computeDirectValues(OntResourceImpl.java:1580)||
>> || at
>>
>> org.apache.jena.ontology.impl.OntResourceImpl.listDirectPropertyValues(OntResourceImpl.java:1553)||
>> || at
>>
>> org.apache.jena.ontology.impl.OntClassImpl.listSuperClasses(OntClassImpl.java:180)||
>> || at
>>
>> org.apache.jena.ontology.impl.OntClassImpl.isHierarchyRoot(OntClassImpl.java:739)||
>> || 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 com.company.Main.main(Main.java:25)|
>>
>>
>>
>> On 05.09.19 03:11, Alex To wrote:
>>> Hi I am trying to load schema.org ontology and get all top classes
>>> using ontModel.listHierarchyRootClasses() but can't get the expected
>>> results with different OntModelSpec.
>>>
>>> If I use OWL_MEM, it lists 2500+ records with all the records have "null"
>>> URI.
>>> If I use OWL_DL_MEM, it lists 0 records
>>>
>>> The code is very simple as follows
>>>
>>> Model model = ModelFactory.createDefaultModel();
>>> model.read("https://schema.org/docs/schemaorg.owl");
>>> OntModel ontModel =
>>> ModelFactory.createOntologyModel(OntModelSpec.OWL_MEM, model);
>>> ExtendedIterator<OntClass> topClazzez =
>> ontModel.listHierarchyRootClasses();
>>> while (topClazzez.hasNext()) {
>>> OntClass clazz = topClazzez.next();
>>> System.out.println(clazz.getURI());
>>> }
>>>
>>> A minimal Maven project ready to run to demonstrate my problem is here
>>> https://github.com/AlexTo/jena-lab (have a look at the Main.java)
>>>
>>> Thanks a lot
>
> --
>
Re: How to use ontModel.listHierarchyRootClasses() properly
Posted by Alex To <to...@gmail.com>.
Thanks Lorenz
I figured out the union thing too so I ended up using the below SPARQL
instead and it seems to work fine but would love to know what is the
equivalent using Jena API
"SELECT DISTINCT ?s WHERE { " +
"?s a owl:Class . " +
"FILTER (!isBlank(?s)) " +
"FILTER (?s != owl:Thing && ?s != owl:Nothing) . " +
"OPTIONAL { " +
" ?s rdfs:subClassOf ?super . " +
" FILTER (?super != rdfs:Resource && ?super != owl:Thing
&& ?s != ?super) " +
" } . " +
"FILTER (!bound(?super))" +
"}");
Regards
On Thu, Sep 5, 2019 at 8:00 PM Lorenz Buehmann <
buehmann@informatik.uni-leipzig.de> wrote:
> schema.org contains a bunch of anonymous classes like the union of other
> classes which are used as domain or range of a property, that's why you
> get null values because they do not have a URI. If you'd just call
>
> |System.out.println(clazz);|
>
>
> you'd see the blank node Ids.
>
>
> Among all those blank nodes, there is indeed the one top level class
> http://schema.org/Thing .
>
>
> I thought just adding a filter on the iterator is enough, i.e.
>
> |topClazzez = topClazzez.filterDrop(OntResource::isAnon);|
>
>
> but while it doesn't return the blank nodes anymore, it leads to an
> exception:
>
>
> |Exception in thread "main"
> org.apache.jena.ontology.ConversionException: Cannot convert node
> http://www.w3.org/2000/01/rdf-schema#Class 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$8(OntResourceImpl.java:1536)||
> || at
> org.apache.jena.util.iterator.Map1Iterator.next(Map1Iterator.java:46)||
> || at
>
> org.apache.jena.ontology.impl.OntResourceImpl.computeDirectValues(OntResourceImpl.java:1580)||
> || at
>
> org.apache.jena.ontology.impl.OntResourceImpl.listDirectPropertyValues(OntResourceImpl.java:1553)||
> || at
>
> org.apache.jena.ontology.impl.OntClassImpl.listSuperClasses(OntClassImpl.java:180)||
> || at
>
> org.apache.jena.ontology.impl.OntClassImpl.isHierarchyRoot(OntClassImpl.java:739)||
> || 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 com.company.Main.main(Main.java:25)|
>
>
>
> On 05.09.19 03:11, Alex To wrote:
> > Hi I am trying to load schema.org ontology and get all top classes
> > using ontModel.listHierarchyRootClasses() but can't get the expected
> > results with different OntModelSpec.
> >
> > If I use OWL_MEM, it lists 2500+ records with all the records have "null"
> > URI.
> > If I use OWL_DL_MEM, it lists 0 records
> >
> > The code is very simple as follows
> >
> > Model model = ModelFactory.createDefaultModel();
> > model.read("https://schema.org/docs/schemaorg.owl");
> > OntModel ontModel =
> > ModelFactory.createOntologyModel(OntModelSpec.OWL_MEM, model);
> > ExtendedIterator<OntClass> topClazzez =
> ontModel.listHierarchyRootClasses();
> > while (topClazzez.hasNext()) {
> > OntClass clazz = topClazzez.next();
> > System.out.println(clazz.getURI());
> > }
> >
> > A minimal Maven project ready to run to demonstrate my problem is here
> > https://github.com/AlexTo/jena-lab (have a look at the Main.java)
> >
> > Thanks a lot
>
--
Re: How to use ontModel.listHierarchyRootClasses() properly
Posted by Lorenz Buehmann <bu...@informatik.uni-leipzig.de>.
schema.org contains a bunch of anonymous classes like the union of other
classes which are used as domain or range of a property, that's why you
get null values because they do not have a URI. If you'd just call
|System.out.println(clazz);|
you'd see the blank node Ids.
Among all those blank nodes, there is indeed the one top level class
http://schema.org/Thing .
I thought just adding a filter on the iterator is enough, i.e.
|topClazzez = topClazzez.filterDrop(OntResource::isAnon);|
but while it doesn't return the blank nodes anymore, it leads to an
exception:
|Exception in thread "main"
org.apache.jena.ontology.ConversionException: Cannot convert node
http://www.w3.org/2000/01/rdf-schema#Class 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$8(OntResourceImpl.java:1536)||
|| at
org.apache.jena.util.iterator.Map1Iterator.next(Map1Iterator.java:46)||
|| at
org.apache.jena.ontology.impl.OntResourceImpl.computeDirectValues(OntResourceImpl.java:1580)||
|| at
org.apache.jena.ontology.impl.OntResourceImpl.listDirectPropertyValues(OntResourceImpl.java:1553)||
|| at
org.apache.jena.ontology.impl.OntClassImpl.listSuperClasses(OntClassImpl.java:180)||
|| at
org.apache.jena.ontology.impl.OntClassImpl.isHierarchyRoot(OntClassImpl.java:739)||
|| 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 com.company.Main.main(Main.java:25)|
On 05.09.19 03:11, Alex To wrote:
> Hi I am trying to load schema.org ontology and get all top classes
> using ontModel.listHierarchyRootClasses() but can't get the expected
> results with different OntModelSpec.
>
> If I use OWL_MEM, it lists 2500+ records with all the records have "null"
> URI.
> If I use OWL_DL_MEM, it lists 0 records
>
> The code is very simple as follows
>
> Model model = ModelFactory.createDefaultModel();
> model.read("https://schema.org/docs/schemaorg.owl");
> OntModel ontModel =
> ModelFactory.createOntologyModel(OntModelSpec.OWL_MEM, model);
> ExtendedIterator<OntClass> topClazzez = ontModel.listHierarchyRootClasses();
> while (topClazzez.hasNext()) {
> OntClass clazz = topClazzez.next();
> System.out.println(clazz.getURI());
> }
>
> A minimal Maven project ready to run to demonstrate my problem is here
> https://github.com/AlexTo/jena-lab (have a look at the Main.java)
>
> Thanks a lot