Protege中的SPARQL-计算xsd：Integer结果的平均值时出现问题

Question

我有以下查询：

SELECT  ?duration

WHERE { 
?class rdfs:label ?className . 
FILTER regex(?className, "yoga").
?class chris:hasDurationMinutes ?duration.
 }

执行返回后：

duration
"45"^^<http://www.w3.org/2001/XMLSchema#integer>    
"45"^^<http://www.w3.org/2001/XMLSchema#integer>    
"60"^^<http://www.w3.org/2001/XMLSchema#integer>

我正在尝试查找这些值的平均值，因此使用了avg聚合器：

SELECT  avg(?duration)

WHERE { 
?class rdfs:label ?className . 
FILTER regex(?className, "yoga").
?class chris:hasDurationMinutes ?duration.
 }

但是当我在Protege中运行时，我得到以下堆栈

org.protege.editor.owl.rdf.SparqlReasonerException: org.openrdf.query.MalformedQueryException: Encountered " "avg" "avg "" at line 7, column 9.

期待以下项目之一：“（” ...“ *” ...“与众不同” ...“减少” .........

at org.protege.editor.owl.rdf.repository.BasicSparqlReasoner.executeQuery(BasicSparqlReasoner.java:90)
at org.protege.editor.owl.rdf.SparqlQueryView.lambda$createBottomComponent$0(SparqlQueryView.java:67)
at javax.swing.AbstractButton.fireActionPerformed(AbstractButton.java:2022)
at javax.swing.AbstractButton$Handler.actionPerformed(AbstractButton.java:2348)
at javax.swing.DefaultButtonModel.fireActionPerformed(DefaultButtonModel.java:402)
at javax.swing.DefaultButtonModel.setPressed(DefaultButtonModel.java:259)
at javax.swing.plaf.basic.BasicButtonListener.mouseReleased(BasicButtonListener.java:252)
at java.awt.Component.processMouseEvent(Component.java:6533)
at javax.swing.JComponent.processMouseEvent(JComponent.java:3324)
at java.awt.Component.processEvent(Component.java:6298)
at java.awt.Container.processEvent(Container.java:2236)
at java.awt.Component.dispatchEventImpl(Component.java:4889)
at java.awt.Container.dispatchEventImpl(Container.java:2294)
at java.awt.Component.dispatchEvent(Component.java:4711)
at java.awt.LightweightDispatcher.retargetMouseEvent(Container.java:4888)
at java.awt.LightweightDispatcher.processMouseEvent(Container.java:4525)
at java.awt.LightweightDispatcher.dispatchEvent(Container.java:4466)
at java.awt.Container.dispatchEventImpl(Container.java:2280)
at java.awt.Window.dispatchEventImpl(Window.java:2746)
at java.awt.Component.dispatchEvent(Component.java:4711)
at java.awt.EventQueue.dispatchEventImpl(EventQueue.java:758)
at java.awt.EventQueue.access$500(EventQueue.java:97)
at java.awt.EventQueue$3.run(EventQueue.java:709)
at java.awt.EventQueue$3.run(EventQueue.java:703)
at java.security.AccessController.doPrivileged(Native Method)
at java.security.ProtectionDomain$JavaSecurityAccessImpl.doIntersectionPrivilege(ProtectionDomain.java:80)
at java.security.ProtectionDomain$JavaSecurityAccessImpl.doIntersectionPrivilege(ProtectionDomain.java:90)
at java.awt.EventQueue$4.run(EventQueue.java:731)
at java.awt.EventQueue$4.run(EventQueue.java:729)
at java.security.AccessController.doPrivileged(Native Method)
at java.security.ProtectionDomain$JavaSecurityAccessImpl.doIntersectionPrivilege(ProtectionDomain.java:80)
at java.awt.EventQueue.dispatchEvent(EventQueue.java:728)
at java.awt.EventDispatchThread.pumpOneEventForFilters(EventDispatchThread.java:201)
at java.awt.EventDispatchThread.pumpEventsForFilter(EventDispatchThread.java:116)
at java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:105)
at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:101)
at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:93)
at java.awt.EventDispatchThread.run(EventDispatchThread.java:82)

原因：org.openrdf.query.MalformedQueryException：在第7行第9列遇到““ avg”“ avg”“期望以下之一：“（” ...“ *” ...“与众不同” ...“减少” .........

at org.openrdf.query.parser.sparql.SPARQLParser.parseQuery(SPARQLParser.java:198)
at org.openrdf.query.parser.QueryParserUtil.parseQuery(QueryParserUtil.java:136)
at org.openrdf.repository.sail.SailRepositoryConnection.prepareQuery(SailRepositoryConnection.java:152)
at org.openrdf.repository.sail.SailRepositoryConnection.prepareQuery(SailRepositoryConnection.java:55)
at org.openrdf.repository.base.RepositoryConnectionBase.prepareQuery(RepositoryConnectionBase.java:118)
at org.protege.editor.owl.rdf.repository.BasicSparqlReasoner.executeQuery(BasicSparqlReasoner.java:69)
... 37 more

原因：org.openrdf.query.parser.sparql.ast.ParseException：在第7行第9列遇到““ avg”“ avg”“期望以下之一：“（” ...“ *” ...“与众不同” ...“减少” .........

at org.openrdf.query.parser.sparql.ast.SyntaxTreeBuilder.generateParseException(SyntaxTreeBuilder.java:8943)
at org.openrdf.query.parser.sparql.ast.SyntaxTreeBuilder.jj_consume_token(SyntaxTreeBuilder.java:8813)
at org.openrdf.query.parser.sparql.ast.SyntaxTreeBuilder.Select(SyntaxTreeBuilder.java:464)
at org.openrdf.query.parser.sparql.ast.SyntaxTreeBuilder.SelectQuery(SyntaxTreeBuilder.java:324)
at org.openrdf.query.parser.sparql.ast.SyntaxTreeBuilder.Query(SyntaxTreeBuilder.java:300)
at org.openrdf.query.parser.sparql.ast.SyntaxTreeBuilder.QueryContainer(SyntaxTreeBuilder.java:188)
at org.openrdf.query.parser.sparql.ast.SyntaxTreeBuilder.parseQuery(SyntaxTreeBuilder.java:31)
at org.openrdf.query.parser.sparql.SPARQLParser.parseQuery(SPARQLParser.java:153)
... 42 more

Answer 1

感谢Stansilav提供以下解决了我问题的答案。

select (avg(?duration) as ?avg_duration)