使用SPARQL和Jena检索OWL类层次结构中的所有路径 [英] Retrieving all paths in an OWL class hierarchy with SPARQL and Jena
问题描述
我有一个RDF图，该图的层次结构分为三层.我想检索所有从类层次结构的根(即owl:Thing)到第三级类的所有路径，而无需使用推理程序.例如，我想要一条路
C 1 →
C 2 →
C 3
是一条路径，其中每个
C i
是层次结构中第i 级别的类.
I have an RDF graph of with a hierarchy three levels deep. I want to retrieve all the paths starting from the root of the class hierarchy (i.e., owl:Thing) down to classes in the third level without using a reasoner. For instance, I would like the path
C1 →
C2 →
C3
is a path, where each
Ci
is a class at the ith level of the hierarchy.
我需要使用广度优先搜索算法来检索RDF图中的所有路径，而无需考虑图中的对象属性.
I need to retrieve all the paths in the RDF graph using the breadth first search algorithm with no considerations to the object properties in the graph.
推荐答案
给出一些这样的数据(类名的长度指示类在层次结构中的深度):
Given some data like this (where length of the class name is an indication of the depth of the class in the hierarchy):
@prefix : <http://example.org/> .
@prefix rdfs: <http://www.w3.org/2000/01/rdf-schema#> .
:a a rdfs:Class .
:aa rdfs:subClassOf :a .
:ab rdfs:subClassOf :a .
:ac rdfs:subClassOf :a .
:aaa rdfs:subClassOf :aa .
:aab rdfs:subClassOf :aa .
:aac rdfs:subClassOf :aa .
:aaba rdfs:subClassOf :aab .
:aabb rdfs:subClassOf :aab .
:aba rdfs:subClassOf :ab .
:abb rdfs:subClassOf :ab .
您可以使用SPARQL查询来选择所需的路径.
You can use a SPARQL query to select the paths that you're looking for.
您可以像这样编写SPARQL查询以获得以下结果:
You can write a SPARQL query like this to get the following results:
prefix : <http://example.org/>
prefix rdfs: <http://www.w3.org/2000/01/rdf-schema#>
select ?c1 ?c2 ?c3 where {
values ?c1 { :a }
?c1 ^rdfs:subClassOf ?c2 .
OPTIONAL {
?c2 ^rdfs:subClassOf ?c3 .
}
}
order by ?c3 ?c2 ?c1
-------------------
| c1 | c2 | c3 |
===================
| :a | :ac | |
| :a | :aa | :aaa |
| :a | :aa | :aab |
| :a | :aa | :aac |
| :a | :ab | :aba |
| :a | :ab | :abb |
-------------------
使用相机本体
这种方法适用于已经使用过的相机本体注释中提到的内容，尽管查询需要一些扩展才能处理更深的类路径.因此:
Using the camera ontology
This approach works with the camera ontology that has been mentioned in the comments, though the query requires a little extension to handle deeper class paths. Thus:
PREFIX rdfs: <http://www.w3.org/2000/01/rdf-schema#>
PREFIX owl: <http://www.w3.org/2002/07/owl#>
PREFIX : <http://www.xfront.com/owl/ontologies/camera/#>
select * where {
values ?c1 { owl:Thing }
?c1 ^rdfs:subClassOf ?c2 .
OPTIONAL {
?c2 ^rdfs:subClassOf ?c3 .
OPTIONAL {
?c3 ^rdfs:subClassOf ?c4 .
}
}
}
order by ?c4 ?c3 ?c2
-----------------------------------------------------------
| c1 | c2 | c3 | c4 |
===========================================================
| owl:Thing | :Money | | |
| owl:Thing | :Range | | |
| owl:Thing | :Window | | |
| owl:Thing | :PurchaseableItem | :Body | |
| owl:Thing | :PurchaseableItem | :Lens | |
| owl:Thing | :PurchaseableItem | :Camera | :Digital |
| owl:Thing | :PurchaseableItem | :Camera | :Large-Format |
-----------------------------------------------------------
使用Jena API
虽然上面的SPARQL查询按照广度优先遍历的顺序生成路径，但实际上并不能保证 ARQ生成结果的方式.我们还可以使用Jena Model API检索子类来直接实现广度优先搜索.这是一个简单的实现:
Using the Jena API
While the above SPARQL query produces the paths in the order that would expected from a breadth first traversal, there is actually no guarantee on how ARQ generates the results. We can also implement a Breadth First Search directly, using the Jena Model API to retrieve subclasses. Here's a straightforward implementation:
import java.io.IOException;
import java.io.InputStream;
import java.util.ArrayList;
import java.util.LinkedList;
import java.util.List;
import java.util.Queue;
import com.hp.hpl.jena.rdf.model.Model;
import com.hp.hpl.jena.rdf.model.ModelFactory;
import com.hp.hpl.jena.rdf.model.Resource;
import com.hp.hpl.jena.rdf.model.StmtIterator;
import com.hp.hpl.jena.vocabulary.OWL;
import com.hp.hpl.jena.vocabulary.RDFS;
public class BFSInRDFWithJena {
public static List<List<Resource>> BFS( final Model model, final Queue<List<Resource>> queue, final int depth ) {
final List<List<Resource>> results = new ArrayList<>();
while ( !queue.isEmpty() ) {
final List<Resource> path = queue.poll();
results.add( path );
if ( path.size() < depth ) {
final Resource last = path.get( path.size() - 1 );
final StmtIterator stmt = model.listStatements( null, RDFS.subClassOf, last );
while ( stmt.hasNext() ) {
final List<Resource> extPath = new ArrayList<>( path );
extPath.add( stmt.next().getSubject().asResource() );
queue.offer( extPath );
}
}
}
return results;
}
public static void main( final String[] args ) throws IOException {
final Model model = ModelFactory.createDefaultModel();
try ( final InputStream in = BFSInRDFWithJena.class.getClassLoader().getResourceAsStream( "camera.owl" ) ) {
model.read( in, null );
}
// setup the initial queue
final Queue<List<Resource>> queue = new LinkedList<>();
final List<Resource> thingPath = new ArrayList<>();
thingPath.add( OWL.Thing );
queue.offer( thingPath );
// Get the paths, and display them
final List<List<Resource>> paths = BFS( model, queue, 4 );
for ( List<Resource> path : paths ) {
System.out.println( path );
}
}
}
[http://www.w3.org/2002/07/owl#Thing]
[http://www.w3.org/2002/07/owl#Thing, http://www.xfront.com/owl/ontologies/camera/#PurchaseableItem]
[http://www.w3.org/2002/07/owl#Thing, http://www.xfront.com/owl/ontologies/camera/#Window]
[http://www.w3.org/2002/07/owl#Thing, http://www.xfront.com/owl/ontologies/camera/#Range]
[http://www.w3.org/2002/07/owl#Thing, http://www.xfront.com/owl/ontologies/camera/#Money]
[http://www.w3.org/2002/07/owl#Thing, http://www.xfront.com/owl/ontologies/camera/#PurchaseableItem, http://www.xfront.com/owl/ontologies/camera/#Camera]
[http://www.w3.org/2002/07/owl#Thing, http://www.xfront.com/owl/ontologies/camera/#PurchaseableItem, http://www.xfront.com/owl/ontologies/camera/#Lens]
[http://www.w3.org/2002/07/owl#Thing, http://www.xfront.com/owl/ontologies/camera/#PurchaseableItem, http://www.xfront.com/owl/ontologies/camera/#Body]
[http://www.w3.org/2002/07/owl#Thing, http://www.xfront.com/owl/ontologies/camera/#PurchaseableItem, http://www.xfront.com/owl/ontologies/camera/#Camera, http://www.xfront.com/owl/ontologies/camera/#Digital]
[http://www.w3.org/2002/07/owl#Thing, http://www.xfront.com/owl/ontologies/camera/#PurchaseableItem, http://www.xfront.com/owl/ontologies/camera/#Camera, http://www.xfront.com/owl/ontologies/camera/#Large-Format]
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