No, why do you think so? ?v is the variable that gets assigned a vehicle
for which you compute the avg speed.
<Instance> should be ?v, i.e. you have to group by it and select it
INSERT {
?v :avgSpeed ?avg
} WHERE {
SELECT ?v (AVG(?speed) AS ?avg) {
....
} GROUP BY ?v
}
On 05.06.2017 17:03, Aya Hamdy wrote:
Hello,
I will try to explain with examples. I have generated my ontology from
Protege and converted it to turtle syntax via an online tool.
*I have a class for average speed sensors:*
###
http://www.semanticweb.org/toshiba/ontologies/2017/3/
untitled-ontology-6#Avg_Speed_Sensor
untitled-ontology-6:Avg_Speed_Sensor rdf:type owl:Class ;
rdfs:subClassOf
untitled-ontology-6:Sensor ,
untitled-ontology-6:Speed_Sensor .
*and a class for vehicles:*
###
http://www.semanticweb.org/toshiba/ontologies/2017/3/
untitled-ontology-6#Vehicle
untitled-ontology-6:Vehicle rdf:type owl:Class .
*The vehicle class has a property called vehicleSpeed:*
###
http://www.semanticweb.org/toshiba/ontologies/2017/3/
untitled-ontology-6#vehicleSpeed
untitled-ontology-6:vehicleSpeed rdf:type owl:DatatypeProperty ;
rdfs:domain untitled-ontology-6:Vehicle
;
rdfs:range xsd:integer .
*The avg speed sensor class has a property called recorded_speed:*
###
http://www.semanticweb.org/toshiba/ontologies/2017/3/
untitled-ontology-6#recorded_speed
untitled-ontology-6:recorded_speed rdf:type owl:DatatypeProperty ;
rdfs:domain
untitled-ontology-6:Sensor ,
untitled-ontology-6:Speed_Sensor ;
rdfs:range xsd:integer .
The recorded speed by the avg speed sensor allocated to a specific road
is
the average of the vehicleSpeeds of the vehicles on that specific road,
where the avg speed sensor class has a property called
avgSpeedSensor_Infrastructure and the vehicle has a property called
Vehicle_Road.
I have two vehicle instances: Vehicle1 and Vehicle2; and two sensor
instances: SpeedSensor1 and SpeedSensor2.
Is it clearer now or just confusing?
so I am guessing following your guide it would be something like:
INSERT {
<instance> :avgSpeed ?avg
}
WHERE {
SELECT (AVG(?speed) AS ?avg) {
?v rdf:type :Vehicle ;
:vehicleSpeed ?speed;
: Vehicle_Road ?r;
?avs rdf:type :Avg_Speed_Sensor;
:avgSpeedSensor_Infrastructure ?r
}
}
But the value of the <instance> should come from reading the file,
right?
On Sun, Jun 4, 2017 at 9:04 PM, Andy Seaborne <[email protected]> wrote:
On 04/06/17 18:47, Aya Hamdy wrote:
Hello,
I wanted to add a property called avgSpeed to an instance of a class
called
FlowSensor. This property should be the average of the values of the
property vehicleSpeed attached to instances of the class Vehicle.
I read that SPARQL update allows doing this. However, I cannot reach
the
syntax for doing the* averaging of values* or for building the *SPARQL
Update *query using jena with eclipse on the jena website.
If Jena indeed supports doing what I intend to do then can someone
point
out some sources to guide me in my attempt?
Best Regards,
Aya
Calculate the average in a nested select so somethign like (you'll have
to
fix this up):
INSERT {
<instance> :avgSpeed ?avg
}
WHERE {
SELECT (AVG(?speed) AS ?avg) {
?v rdf:type :Vehicle ;
:vehicleSpeed ?speed
}
}
By the way - it is better to more concrete in your description - actual
data for example.
