Hi Rich,
one way of computing and returning multiple values at once is to use
magic properties, but those are limited in that they do not support
aggregations in the SELECT clause.
But do you really run into performance issues where this would make a
difference? If yes, then using ui:Functions could theoretically be a
solution:
http://www.topquadrant.com/2013/06/18/defining-sparql-functions-with-swp/
These are SPIN functions that have an SWP "script" as body, and in that
script you can implement any sophisticated logic that you like, e.g. to
pre-compute certain values and put them into a temporary graph
(ui:tempGraph), then have the aggregations walk that temporary graph
only. Note that those functions can still only return a single value,
but they could return something like a comma-separated string list...
Holger
On 3/19/2014 9:25, Rich Keller wrote:
Holger: I have a followup question. Creating a SPIN function that
performs the summation works well for computing a single sum to be
passed back as the function's return value. In my actual case, I'm
trying to calculate multiple sums and return them. While I could write
a more general function (or template) and call it several times to
compute several sums, that is quite inefficient because it will
require performing essentially the same SPARQL Select N times, once
for each datatype property I wish to sum over.
Can you suggest an alternative approach that would be more efficient?
Thanks for your help,
Rich
On Tuesday, March 18, 2014 9:25:30 AM UTC-7, Rich Keller wrote:
Thanks Holger. I will try that. Rich
On Monday, March 17, 2014 3:57:32 PM UTC-7, Holger Knublauch wrote:
Hi Rich,
in general, nested sub-selected do not see the bindings of
variables from the outer query. If you want to perform an
aggregation, try turning the inner SELECT into a SPIN function
where you can explicitly pass the required arguments. E.g. the
spin:body of that function ex:myCount would be
SELECT ((SUM(?hourlyCount)) AS ?dailyCount)
WHERE {
?arg1 :xday ?day . #Should bind ?day to the
:xday value for the specific instance over which the rule is
firing
?hourly :day ?day .
?hourly :count ?hourlyCount .
}
where ?arg1 is substituted with ?this when you call it in the
rule:
CONSTRUCT {
?this :xcount ?dailyCount .
}
WHERE {
BIND (ex:myCount(?this) AS ?dailyCount) .
}
HTH
Holger
On 3/18/2014 8:37, Rich Keller wrote:
Hi. I have been having trouble with a SPIN rule I've
constructed to aggregate a set of values. It seems as if the
variable ?*this* is not being bound properly, and I wonder if
this is due to my SPARQL formulation or to TBC.
Here is the problem. Conceptually, there are counts of a
particular phenomenon occurring on a given day during a given
hour: <day, hour, count>. The rule's task is to sum the
counts for each hour, and assign that sum to the count for
the appropriate day. The SPIN rule is defined for a 'Daily'
object (representing a day); the counts are assigned to
'Hourly' objects (representing an hour of a particular day).
I assumed that the aggregation function SUM (in the rule
below) would sum over only the counts for a single day,
because I constrained the variable ?day using ?*this*.
However, the results indicate that the day was not
constrained because the sum for each day is the same: the
grand total of all counts over all days. Perhaps I do not
understand the scoping rules for ?*this* within the SPARQL
expression.
Any guidance would be appreciated! When I execute the SELECT
clause alone in the SPARQL Query Editor, substituting a
specific 'Daily' instance for ?*this*, I do get the desired
sum for the hours in that day.
Thanks,
Rich
:Daily a owl:Class ;
spin:rule
"CONSTRUCT {
?this :xcount ?dailyCount .
}
WHERE {
{
SELECT ((SUM(?hourlyCount)) AS ?dailyCount)
WHERE {
?this :xday ?day . #Should bind ?day to the
:xday value for the specific instance over which the rule is
firing
?hourly :day ?day .
?hourly :count ?hourlyCount .
}
} .
}"
:D1 a :Daily;
:xday 1 .
:D2 a :Daily;
:xday 2 .
:Hourly a owl:Class .
:H1D1 a :Hourly;
:count 10 ;
:hour 1 ;
:day 1 .
:H2D1 a :Hourly;
:count 10 ;
:hour 2 ;
:day 1 .
:H3D1 a :Hourly;
:count 10 ;
:hour 3 ;
:day 1 .
:H1D2 a :Hourly;
:count 10 ;
:hour 1 ;
:day 2 .
:H2D2 a :Hourly;
:count 10 ;
:hour 2 ;
:day 2 .
----------------
Inference Result:
:D1 :xcount 50
:D2 :xcount 50
Expected Result:
:D1 :xcount 30
:D2 :xcount 20
--
-- You received this message because you are subscribed to
the Google
Group "TopBraid Suite Users", the topics of which include
Enterprise Vocabulary Network (EVN), TopBraid Composer,
TopBraid Live, TopBraid Insight, SPARQLMotion, SPARQL Web
Pages and SPIN.
To post to this group, send email to
[email protected]
To unsubscribe from this group, send email to
[email protected]
For more options, visit this group at
http://groups.google.com/group/topbraid-users?hl=en
<http://groups.google.com/group/topbraid-users?hl=en>
---
You received this message because you are subscribed to the
Google Groups "TopBraid Suite Users" group.
To unsubscribe from this group and stop receiving emails from
it, send an email to [email protected].
For more options, visit https://groups.google.com/d/optout
<https://groups.google.com/d/optout>.
--
-- You received this message because you are subscribed to the Google
Group "TopBraid Suite Users", the topics of which include Enterprise
Vocabulary Network (EVN), TopBraid Composer, TopBraid Live, TopBraid
Insight, SPARQLMotion, SPARQL Web Pages and SPIN.
To post to this group, send email to
[email protected]
To unsubscribe from this group, send email to
[email protected]
For more options, visit this group at
http://groups.google.com/group/topbraid-users?hl=en
---
You received this message because you are subscribed to the Google
Groups "TopBraid Suite Users" group.
To unsubscribe from this group and stop receiving emails from it, send
an email to [email protected]
<mailto:[email protected]>.
For more options, visit https://groups.google.com/d/optout.
--
-- You received this message because you are subscribed to the Google
Group "TopBraid Suite Users", the topics of which include Enterprise Vocabulary
Network (EVN), TopBraid Composer, TopBraid Live, TopBraid Insight, SPARQLMotion, SPARQL
Web Pages and SPIN.
To post to this group, send email to
[email protected]
To unsubscribe from this group, send email to
[email protected]
For more options, visit this group at
http://groups.google.com/group/topbraid-users?hl=en
---
You received this message because you are subscribed to the Google Groups "TopBraid Suite Users" group.
To unsubscribe from this group and stop receiving emails from it, send an email
to [email protected].
For more options, visit https://groups.google.com/d/optout.
