Regions of adjacent line portions with the same dataproperties in Protégé 5

user_13818049 0
Viewed 52

I try to process line-based data using protege 5 and picture similar "regions" of a curve.

So I have a curve, which is deconstructed into portions of equal lengths in my ontology (class Portion, instances p_1, ... ,p_n). The portions are defined by their start- and endpoints (point_1, ... ,point_n+1), furthermore, the radius of the curve is stored in the ontology as data property of the instances (p_1, ... ,p_n). I managed to reason the adjacency relations between the different portions

hasStartPoint(p_2,point_2) o isEndpointOf(point_2,p_1) => isNextOf(p_2, p_1)
hasEndPoint(p_1,point_2) o isStartpointOf(point_2,p_2) => hasNext(p_1, p_2)

I also managed to create defined classes, storing portions with the same radius.

So here is my question: I want to reason the sets of portions (regions), which are adjecent and share the same curve radius. Then, i instances of a class Set should be created, for i different radius and non-adjecent sets, individuals (region1, ... ,regioni).

Here is the exemplary data I want to process: data I want to process

In other words: if a radius appears twice on the given line, and the portions of this radius are not adjacent, they should not be part of the same region. Further, regions should be created automatically when adding portions of different radius. The only idea I have, is to somehow traverse the set of portions with a loop over the isNext triplet, which requires some coding I guess, but I can't find anything alike here...

I hope, my problem is clear and I am happy to read if anybody has an idea on it.

Thank you in advance

Julian

owl-api protege sparql owl
1 Answers

From the owl-api tag, I infer you're looking to write code that uses the OWL API to reach your objective (You didn't mention which reasoner you're using in Protege - you'll need to use the same reasoner in your code to get things like hasNext relations inferred).

In OWL API, I'd do something like the following:

  • Infer the hasNext triples, if they are not already stored in the ontology file
  • For each of the defined classes that separate instances with the same radius
    • Retrieve all individuals of that class
    • Retrieve all property assertions with hasNext
    • Aggregate these instances into regions - e.g., seed one region for each property assertion, then merge two regions if their instances all belong to the same defined class and an endpoint in one region is a startpoint in the other. Repeat until only one region is left for a defined class (I believe, from your problem description, that regions cannot span outside of instances with the same radius) or until no further merges can happen.

In terms of OWLAPI implementation, once you have the ontology loaded in an OWLOntology object, you'd create an OWLReasoner with the OWLReasonerFactory implementation available for the reasoner of your choice (examples of this exist in the OWLAPI wiki), then there are a number of methods that can come in handy: (Referencing OWLAPI 4 here because that's what Protege uses)

  • Get all individuals of a class: OWLOntology::getClassAssertionAxioms(OWLClassExpression) gives all axioms stating an individual belongs to a class, useful to retrieve instances of your defined classes. Through OWLReasoner, you can use OWLReasoner::getInstances(OWLClass)
  • Get all object property assertions for an individual: OWLOntology::getObjectPropertyAssertionAxioms(OWLIndividual). Useful to get hasNext values. Through the reasoner, this would be OWLReasoner::getObjectPropertyValues(OWLNamedIndividual, OWLObjectPropertyExpression)

I believe the rest of the algorithm can be implemented without OWLAPI specific code.

user_11970450
Related