I am working in DBPedia. I am having a problem when using group by in Sparql.
I have this code:
SELECT ?res ?titulo
WHERE {
?res rdf:type <http://dbpedia.org/class/yago/JaguaresDeChiapasFootballers> .
?res rdfs:label ?titulo .
}
GROUP BY (?res)
LIMIT 15
I want to return a list of all in this type. But I only want to return one for each URI, I put the group by and it doesn’t work and I really don’t know why?
Can someone help me?
Your original query isn't legal SPARQL. If you paste it into the SPARQL query validator at sparql.org, you'll get the following message:
Non-group key variable in SELECT: ?titulo
If you group by ?res, then you can't select the non-group variable ?titulo. If you just want one ?titulo value per ?res, then you can use …
select ?res (sample(?titulo) as ?title)
…
SPARQL results
If you want a list of the titles, then you can use group_concat to concatenate the titles:
select ?res (group_concat(?titulo;separator=', ') as ?title)
…
SPARQL results
Related
SELECT ?Name FROM <http://.../biblio.rdf>
WHERE { ?Aut name ?Name . ?Pub author ?Aut . ?Pub conf ?Conf
FILTER (?Conf IN ( SELECT ?ConfX FROM <http://.../biblio.rdf>
WHERE { ?ConfX series "ISWC" }))}
I have taken the query from http://www.renzoangles.net/files/amw2011.pdf.
Getting the malformed query syntax error when I tried the above format in AWS Neptune.
Please help me fix the above query.
If you want to test that a triple is in the data, which seems to be the intention of the exampel of "FILTER IN SELECT " here, yuo can use FILTER EXISTS
FILTER EXISTS { ?Conf series "ISWC" }
Suppose I want to look for some first degree neighbors of Berlin. I ask the following query:
select ?s ?p where {
?s ?p dbr:Berlin.
}
Is it possible to put a restriction on the return result, such that there are at most 5 results for each unique value of ?p?
My attempts with subqueries all time out...
But, as potentially useful if not exactly perfect solution, maybe GROUP_CONCAT, MAX/MIN or SAMPLE are of use?
SELECT
?writer (GROUP_CONCAT(?namestring; SEPARATOR = " ") AS ?namestrings)
(MIN(?namestring) AS ?min_name)
(MAX(?namestring) AS ?max_name)
(SAMPLE(?namestring) AS ?random_name)
(SAMPLE(?namestring) AS ?another_random_name_that_may_unfortunately_be_the_same_again)
WHERE {
?writer wdt:P31 wd:Q5;
wdt:P166 wd:Q37922;
wdt:P735 ?firstname.
?firstname wdt:P1705 ?namestring.
}
GROUP BY ?writer
HAVING ((COUNT(?writer)) > 2 )
LIMIT 20
See it live here.
And, as you can see, SAMPLE is apparently evaluated only once, so using it repeatedly does not get you closer to five (different) samples.
(You can leave out the HAVING for your use. I only included it to restrict it to useful examples))
I've been trying to run a sparql query against https://landregistry.data.gov.uk/app/qonsole# to yield some sold properties result.
The query is the following:
PREFIX xsd: <http://www.w3.org/2001/XMLSchema#>
PREFIX ukhpi: <http://landregistry.data.gov.uk/def/ukhpi/>
SELECT sum(?ukhpi_salesVolume)
WHERE
{ { SELECT ?ukhpi_refMonth ?item
WHERE
{ ?item ukhpi:refRegion <http://landregistry.data.gov.uk/id/region/haringey> ;
ukhpi:refMonth ?ukhpi_refMonth
FILTER ( ?ukhpi_refMonth >= "2019-03"^^xsd:gYearMonth )
FILTER ( ?ukhpi_refMonth < "2020-03"^^xsd:gYearMonth )
}
}
OPTIONAL
{ ?item ukhpi:salesVolume ?ukhpi_salesVolume }
}
The problem is, the result from this is empty. However, if i run the same query without the SUM on the 4th line, i can see there are 11 integer records.
My thoughts are that there is a 12th, empty record which causes all the issues in the SUM operation, but sparql is not my storngest side so i'm not sure how to filter this (and remove any empty records) if that's really the problem.
I've also noticed that most of the aggregate functions do not work as well(min, max, avg). *Count does, and returns 11
I actually solved this myself, all that was needed was a coalesce which apparently existed in sparql too.
So:
SELECT sum(COALESCE(?ukhpi_salesVolume, 0))
instead of just
SELECT sum(?ukhpi_salesVolume)
This is the query and the result:
As you see, I am filtering out the users that are bo:ania, so why do they still appear?
However, if I remove the widecard and select just the users ?user, bo:ania doesn't appear
I didn't provide a minimum data example because this is a question about how filter and wildcard work, not about a problem in extracting some data from a data set. However, if you need a minimum data, I'm more than happy to provide it.
?specificUser is bound to bo:ania by your VALUES statement. ?user is an entirely different binding defined by the other triple patterns. Your FILTER says to filter out results where ?user = bo:ania, and it appears to be doing that correctly, seeing that ?user is not bound to bo:ania in any of the results.
BTW, there isn't a need to use VALUES in this case unless you want to inspect multiple values. If it's just the one value, then the following would work, and not have you wondering why the binding to bo:ania is included in the result set:
SELECT *
WHERE {
?user a rs:user .
?user rs:hasRated ?rating .
?rating rs:hasRatingDate ?ratngDate .
FILTER (?ratingDates >= (now() -"P10000F"^^xsd:duration) )
FILTER (?user != bo:ania)
}
I'm trying to autocomplete what the user writes in an input, with terms in DBpedia, similar to this jsFiddle example. Try writing dog in the input of that jsFiddle, and you will see the 'Dog' term in the suggestions.
I have the following code, and the problem is that the 10-term list I got as a result does not contains the "Dog" alternative. So, if I could order the list by the length of the (string representation of) ?concept, then I could get that term. Is this possible?
SELECT DISTINCT ?concept
WHERE {
?concept a skos:Concept .
FILTER regex(str(?concept), "dog", "i")
}
ORDER BY ASC(?concept) LIMIT 10
So, if I could order the list by the lenght of the ?concept it is possible to get the term. But I can't find the right statement to do it. Is it possible?
It sounds like you're looking for strlen.
order by strlen(str(?concept))
E.g.,
select distinct ?concept where {
?concept a skos:Concept .
filter regex(str(?concept), "dog", "i")
}
order by strlen(str(?concept))
limit 10
SPARQL results
That said, if you're just checking string membership, you don't need all the power of regular expressions, and it might be more efficient to use contains and lcase to check whether the lowercased ?concept contains "dog" with a filter like:
filter contains(lcase(str(?concept)), "dog")
The table of contents in the SPARQL spec has a big list of functions that you can browse. In particular, you'd want to look at the subsections of 17.4 Function Definitions.