我正在尝试从owl文件中提取类的内容，该文件由onProperty和someValuesFrom组成，其中someValueFrom由包含unionOf（onProperty，someValueFrom和equivalentClass）的类组成，我创建了一个SPARQL查询来提取这些数据，但是每次返回空白节点，如“：b0”和“：b1”。有没有人知道我应该如何处理我的查询，以使其提供所需的结果。这是我的猫头鹰文件：
<?xml version="1.0"?>
<rdf:RDF
xmlns="http://owl.cs.manchester.ac.uk/2009/07/sssw/people#"
xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#"
xmlns:xsd="http://www.w3.org/2001/XMLSchema#"
xmlns:rdfs="http://www.w3.org/2000/01/rdf-schema#"
xmlns:owl="http://www.w3.org/2002/07/owl#"
xmlns:ns0="http://owl.cs.manchester.ac.uk/2009/07/sssw/people#"
xml:base="http://owl.cs.manchester.ac.uk/2009/07/sssw/people">
<owl:Ontology rdf:about="http://owl.cs.manchester.ac.uk/2009/07/sssw/people"/>
<owl:Class rdf:about="http://www.w3.org/2002/07/owl#Thing"/>
<owl:Class rdf:about="http://owl.cs.manchester.ac.uk/2009/07/sssw/people#haulage_worker">
<rdfs:comment rdf:datatype="http://www.w3.org/2001/XMLSchema#string"
></rdfs:comment>
<owl:equivalentClass>
<owl:Restriction>
<owl:onProperty>
<owl:ObjectProperty rdf:about="http://owl.cs.manchester.ac.uk/2009/07/sssw/people#works_for"/>
</owl:onProperty>
<owl:someValuesFrom>
<owl:Class>
<owl:unionOf rdf:parseType="Collection">
<owl:Restriction>
<owl:onProperty>
<owl:ObjectProperty rdf:about="http://owl.cs.manchester.ac.uk/2009/07/sssw/people#part_of"/>
</owl:onProperty>
<owl:someValuesFrom>
<owl:Class rdf:about="http://owl.cs.manchester.ac.uk/2009/07/sssw/people#haulage_company"/>
</owl:someValuesFrom>
</owl:Restriction>
<owl:Class rdf:about="http://owl.cs.manchester.ac.uk/2009/07/sssw/people#haulage_company"/>
</owl:unionOf>
</owl:Class>
</owl:someValuesFrom>
</owl:Restriction>
</owl:equivalentClass>
<rdfs:label rdf:datatype="http://www.w3.org/2001/XMLSchema#string"
>haulage worker</rdfs:label>
</owl:Class>
</rdf:RDF>
这是我创建的SPARQL查询：
prefix abc: <http://owl.cs.manchester.ac.uk/2009/07/sssw/people#>
prefix ghi: <http://www.w3.org/1999/02/22-rdf-syntax-ns#>
prefix mno: <http://www.w3.org/2001/XMLSchema#>
prefix owl: <http://www.w3.org/2002/07/owl#>
prefix rdfs: <http://www.w3.org/2000/01/rdf-schema#>
prefix rdf: <http://www.w3.org/1999/02/22-rdf-syntax-ns#>
prefix list: <http://jena.hpl.hp.com/ARQ/list#>
select distinct ?class ?ObjectProperty ?someValuesFrom ?otherClass where { ?class a owl:Class .
OPTIONAL{
?class owl:equivalentClass ?e .
?e a owl:Restriction .
# ?e owl:onProperty ?ObjectProperty .
?e owl:someValuesFrom [ a owl:Class;
owl:unionOf [ rdf:first ? ObjectProperty;
rdf:rest ?someValuesFrom ; rdf:rest*/rdf:first ?otherClass]] .
}
FILTER( STRSTARTS(STR(?class),STR(owl:)) || STRSTARTS(STR(?class),STR(abc:)))
}group by ?class ?ObjectProperty ?someValuesFrom ?otherClass
order by ?class
这是我得到的结果：
-------------------------------------------------------------------------------
| class | ObjectProperty | someValuesFrom | otherClass |
===============================================================================
| abc:haulage_company | | | |
| abc:haulage_worker | _:b0 | _:b1 | _:b0 |
| abc:haulage_worker | _:b0 | _:b1 | abc:haulage_company |
| owl:Thing | | | |
-------------------------------------------------------------------------------
但预期结果是：
-----------------------------------------------------------------------------
| class | ObjectProperty | someValuesFrom | otherClass |
=============================================================================
| abc:haulage_company | | | |
| abc:haulage_worker | abc:works_for | | |
| abc:haulage_worker | abc:part_of | haulage_company | haulage_company |
| owl:Thing | | | |
-----------------------------------------------------------------------------
我应该如何处理SPARQL查询才能返回此结果？
非常感谢提前：）
答案 0 :(得分：1)
如果您在Turtle序列化而不是RDF / XML序列化中查看数据，可能更容易理解SPARQL查询的结果。您数据的相关部分是：
ns0:haulage_worker a owl:Class ;
rdfs:comment ""^^xsd:string ;
rdfs:label "haulage worker"^^xsd:string ;
owl:equivalentClass [ a owl:Restriction ;
owl:onProperty ns0:works_for ;
owl:someValuesFrom [ a owl:Class ;
owl:unionOf ( [ a owl:Restriction ;
owl:onProperty ns0:part_of ;
owl:someValuesFrom ns0:haulage_company
] ns0:haulage_company )
]
考虑关于owl:unionOf的部分的匹配。在您的查询中，它是
owl:unionOf ( [ a owl:Restriction ;
owl:onProperty ns0:part_of ;
owl:someValuesFrom ns0:haulage_company ]
ns0:haulage_company )
列表的元素是具有一些属性的空白节点，ns0:haulage_company。与某些数据匹配的查询是：
owl:unionOf [ rdf:first ?ObjectProperty;
rdf:rest ?someValuesFrom ;
rdf:rest*/rdf:first ?otherClass ]] .
匹配?ObjectProperty的东西是列表的第一个元素，在这种情况下，它不是对象属性，而是一个空白节点。匹配?someValuesFrom的东西是表示列表其余部分的列表节点。
我不太确定你要从这个查询中返回什么。根据您的预期结果，您认为类?class可能与owl:someValuesFrom限制相关，在这种情况下，您希望绑定?ObjectProperty和{{1} }对象属性和类（如果它不是空节点），否则绑定?someValuesFrom到其他相关（非空）类。你说你期望这些结果：
?otherClass但如果我的理解是正确的，我认为获得类似的东西会更容易，更有用：
-----------------------------------------------------------------------------
| class | ObjectProperty | someValuesFrom | otherClass |
=============================================================================
| abc:haulage_company | | | |
| abc:haulage_worker | abc:works_for | | |
| abc:haulage_worker | abc:part_of | haulage_company | haulage_company |
| owl:Thing | | | |
-----------------------------------------------------------------------------
您可以使用以下查询执行此操作：
-----------------------------------------------------------------------------
| class | ObjectProperty | someValuesFrom | otherClass |
=============================================================================
| abc:haulage_company | | | |
| abc:haulage_worker | abc:works_for | | |
| abc:haulage_worker | abc:part_of | haulage_company | |
| abc:haulage_worker | | | haulage_company |
| owl:Thing | | | |
-----------------------------------------------------------------------------
在answer.semanticweb.com问题的答案中描述了保存未绑定到空白节点的值的模式。Binding a variable only when another is non-blank?我们的想法是使用prefix : <http://owl.cs.manchester.ac.uk/2009/07/sssw/people#>
prefix owl: <http://www.w3.org/2002/07/owl#>
prefix rdf: <http://www.w3.org/1999/02/22-rdf-syntax-ns#>
select distinct ?class ?onProperty ?someValuesFrom ?otherClass where {
#-- Select each named class.
?class a owl:Class .
filter( !isBlank( ?class ))
optional {
#-- Find "related" classes by following a somewhat complex
#-- property path that will follow equivalent classes,
#-- existential restrictions, and unionOf expressions.
?class (owl:equivalentClass
|owl:someValuesFrom
|(owl:unionOf/rdf:rest*/rdf:first))+ ?r .
#-- Save non-blank related classes as ?otherClass.
bind(if(isBlank(?r),?unbound,?r) as ?otherClass)
#-- If the related class is a restriction, then we can
#-- take its owl:onProperty and owl:someValuesFrom.
optional {
?r owl:onProperty ?onProperty ;
owl:someValuesFrom ?svf .
bind( if(isBlank(?svf),?unbound,?svf) as ?someValuesFrom )
}
}
}
values ?unbound { UNDEF }
来确保{{1}始终具有未定义的值，然后使用values ?unbound { UNDEF }和?unbound将bind或其他值分配给投影变量。从本质上讲，就是这样：
if结果
?unbound这包括bind(if(isBlank(...),?unbound,...) as ...)
values ?unbound { UNDEF }
的一行，它没有任何其他变量的绑定，但我认为没关系，因为你已经想要-----------------------------------------------------------------------
| class | onProperty | someValuesFrom | otherClass |
=======================================================================
| owl:Thing | | | |
| :haulage_company | | | |
| :haulage_worker | | | |
| :haulage_worker | :works_for | | |
| :haulage_worker | :part_of | :haulage_company | |
| :haulage_worker | | | :haulage_company |
-----------------------------------------------------------------------
和{{1}这样的行}。