SPARQL in Protege - Problem calculating average of xsd:Integer results - sparql

Question

I have the following query:
SELECT ?duration
WHERE {
?class rdfs:label ?className .
FILTER regex(?className, "yoga").
?class chris:hasDurationMinutes ?duration.
}
Which after executing returns:
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>
I'm trying to find the average of these values, so used the avg aggregator:
SELECT avg(?duration)
WHERE {
?class rdfs:label ?className .
FILTER regex(?className, "yoga").
?class chris:hasDurationMinutes ?duration.
}
However when I run in Protege I am getting the following stack
org.protege.editor.owl.rdf.SparqlReasonerException: org.openrdf.query.MalformedQueryException: Encountered " "avg" "avg "" at line 7, column 9.
Was expecting one of:
"(" ...
"*" ...
"distinct" ...
"reduced" ...
...
...
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)
Caused by: org.openrdf.query.MalformedQueryException: Encountered " "avg" "avg "" at line 7, column 9.
Was expecting one of:
"(" ...
"*" ...
"distinct" ...
"reduced" ...
...
...
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
Caused by: org.openrdf.query.parser.sparql.ast.ParseException: Encountered " "avg" "avg "" at line 7, column 9.
Was expecting one of:
"(" ...
"*" ...
"distinct" ...
"reduced" ...
...
...
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

Credit to Stansilav for providing the following answer that resolved my issue.
select (avg(?duration) as ?avg_duration)