使用OWLAPi和JFact推理器获取特定类的所有个体 [英] getting all individuals of a specific class using OWLAPi and JFact reasoner

问题描述

有没有办法让使用推理器的特定班级的所有人？
推理因为我希望获得该类的所有推断和已确认的个体。
我正在使用JFact推理器，我正在尝试循环和if语句。而且我想找到班级的人，例如人。但我无法看到这些人。对于下面的代码有什么想法，或者是否有任何方法用于此目的？

Is there any way to get all individuals of a specific class using reasoner? Reasoner because i want to get all the inferred and assereted individuals of that class. I am using JFact reasoner, and i am trying for loops and if statement. And i want to find the individuals of class e.g "person". But i am unable to see the individuals. Any idea about below code or is there any method for this purpose?

for (OWLClass c : myPizza.getClassesInSignature()) {
        NodeSet<OWLNamedIndividual> instances = reasoner.getInstances(c, true);
        System.out.println(c.getIRI().getFragment());
        if (c.getIRI().getFragment().equals("Person")){

            for (OWLNamedIndividual i : instances.getFlattened()) {
                System.out.println(i.getIRI().getFragment()); 

        }
    }
        else {
            continue;
        }
        break;

    }

谢谢

推荐答案

调用 reasoner.getInstances（c，true）; 只会给你/ c的/ direct /实例;如果你所追求的个体是c的子类的实例，它们将被跳过。切换到 reasoner.getInstances（c，false）; 以包含子类的实例。

Calling reasoner.getInstances(c, true); will only give you the /direct/ instances of c; if the individuals you are after are instances of subclasses of c, they will be skipped. Switch to reasoner.getInstances(c, false); to include instances of subclasses.

您还在调用<第一次迭代后code> break; 。如果 person 不是签名中的第一个类，您将永远不会查找 person 的实例。

You are also calling break; after the first iteration. If person is not the first class in the signature, you'll never look for instances of person.

您可以稍微更改您的代码以减少推理工作：

You could slightly change your code to do less reasoning work:

for (OWLClass c : myPizza.getClassesInSignature()) {
    if (c.getIRI().getFragment().equals("Person")){
        NodeSet<OWLNamedIndividual> instances = reasoner.getInstances(c, false);
        System.out.println(c.getIRI().getFragment());
        for (OWLNamedIndividual i : instances.getFlattened()) {
            System.out.println(i.getIRI().getFragment()); 
        }
    }
}

编辑：注释中的注释，如果您希望看到SWRL推断的个体，您需要使用支持SWRL的推理器，如Pellet或HermiT。 JFact不支持SWRL规则。

Note from comments, if you expect to see SWRL inferred individuals you need to use a reasoner that supports SWRL, like Pellet or HermiT. JFact does not support SWRL rules.

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