I use this sparql query to get as much cities as possible:
select * where {
?city rdf:type dbo:PopulatedPlace
}
However, some expected ones are missing e.g.
http://dbpedia.org/resource/Heidelberg
(neither that nor one of its wikiRedirects)
which is of a dbo:PopulatedPlace as this query returns true (in JSON):
ask {
:Heidelberg a dbo:PopulatedPlace
}
I need that list to be exhaustiv because later I will add constraints based on user input.
I use http://dbpedia.org/snorql/ to test the queries.
Any help is appreciated.
UPDATE:
One of the Devs told me the public endpoint is limited ( about 1K ).
I'll come up with a paginated solution and see if it contains the 'outlier'.
UPDATE2:
The outlier is definitly in the resultset of rdf:type dbo:Town.
Using dbo:PopulatedPlace yields too many results to check per hand, though.
The public endpoint limits results to about 1K. Pagination or use of a smaller subclass of dbo:PopulatedPlace yields the result.
Related
Howto get a list of the top 10 highest mountains from dbpedia ?
I don't know howto start, because I already fail by looking for the correct properties of a specific mountain.
I can't find any property of 'elevation' or 'altitude' in
http://dbpedia.org/page/Mount_Everest
I thought that an interesting property would be the elevation ?
Can someone help ?
This is a problem with publicly curated data, there's no formal schema, so some of the mountains have dbo:elevation (http://dbpedia.org/page/Lhotse) and some only have dbp:elevationRef (http://dbpedia.org/page/K2). You have two options, one technical, one socially beneficial.
Technical option would be a query to get the top 14 and use post processing on the string "(Ranking x)" to get the top 10.
SELECT DISTINCT ?mountain ?rank
WHERE {
?mountain dbp:listing dbr:Eight-thousander.
?mountain dbp:elevationRef ?rank.
}
Socially beneficial solution is to go through those mountains in the Eight-thousander category on Wikipedia and make sure they all have the elevation property set in their description boxes so that DBpedia will scrape it and you can run the query you want:
SELECT DISTINCT ?mountain ?elevation
WHERE {
?mountain dbp:listing dbr:Eight-thousander.
?mountain dbo:elevation ?elevation.
}
ORDER BY DESC(?elevation)
LIMIT 10
I have a data source file that one of its properties is an actual class instance:
<clinic:Radiology rdf:ID="rad1234">
<clinic:diagnosis>Stage 4</clinic:diagnosis>
<clinic:ProvidedBy rdf:resource="#MountSinai"/>
<clinic:ReceivedBy rdf:resource="#JohnSmith"/>
<clinic:patientId>7890123</clinic:patientId>
<clinic:radiologyDate>01-01-2017</clinic:radiologyDate>
</clinic:Radiology>
so clinic:ProvidedBy is pointing to this:
<clinic:Radiologists rdf:ID="MountSinai">
<clinic:name>Mount Sinai</clinic:name>
<clinic:npi>1234567</clinic:npi>
<clinic:specialty>Oncology</clinic:specialty>
</clinic:Radiologists>
How do I query using the property clinic:providedBy (which is of type clinic:Radiologists)? Whatever I have tried does not bring back results.
It's also not clear what exactly you want to have, so my answer will return "all radiology resources that are provided by MountSinai":
PREFIX clinic: <THE NAMESPACE OF_THE_CLINIC_PREFIX>
PREFIX : <THE_BASE_NAMESPACE_OF_YOUR_RDF_DOCUMENT>
SELECT DISTINCT ?s WHERE {
?s clinic:ProvidedBy :MountSinai
}
But, I really suggest to start with an RDF and SPARQL tutorial, since form your comment your query
SELECT * WHERE { ?x rdf:resource "#MountSinai" }
is missing fundamental SPARQL basics. And for writing a matching SPARQL query it'S always good to have a look at the data in Turtle resp. N-Triples format both of which being closer to the SPARQL syntax.
I am trying to teach myself this weekend how to run API queries against a data source in this case data.gov. At first I thought I'd use a simple SQL variant, but it seems in this case I have to use SPARQL.
I've read through the documentation, downloaded Twinkle, and can't seem to quite get it to run. Here is an example of a query I'm running. I'm basically trying to find all gas stations that are null around Denver, CO.
PREFIX station: https://api.data.gov/nrel/alt-fuel-stations/v1/nearest.json?api_key=???location=Denver+CO
SELECT *
WHERE
{ ?x station:network ?network like "null"
}
Any help would be very much appreciated.
SPARQL is a graph pattern language for RDF triples. A query consists of a set of "basic graph patterns" described by triple patterns of the form <subject>, <predicate>, <object>. RDF defines the subject and predicate with URI's and the object is either a URI (object property) or literal (datatype or language-tagged property). Each triple pattern in a query must therefore have three entities.
Since we don't have any examples of your data, I'll provide a way to explore the data a bit. Let's assume your prefix is correctly defined, which I doubt - it will not be the REST API URL, but the URI of the entity itself. Then you can try the following:
PREFIX station: <http://api.data.gov/nrel...>
SELECT *
WHERE
{ ?s station:network ?network .
}
...setting the PREFIX to correctly represent the namespace for network. Then look at the binding for ?network and find out how they represent null. Let's say it is a string as you show. Then the query would look like:
PREFIX station: <http://api.data.gov/nrel...>
SELECT ?s
WHERE
{ ?s station:network "null" .
}
There is no like in SPARQL, but you could use a FILTER clause using regex or other string matching features of SPARQL.
And please, please, please google "SPARQL" and "RDF". There is lots of information about SPARQL, and the W3C's SPARQL 1.1 Query Language Recommendation is a comprehensive source with many good examples.
I have a query to get some similar instances for a specific instance, which is owbes:Dies_Irae instance. This is the query:
CONSTRUCT { ?recommendable0 ?predicate0 ?similarity0 } WHERE {
?recommendable0 ?predicate0 ?object0.
owbes:Dies_Irae ?predicate0 ?object0.
?predicate0 owbes:hasSimilarityValue ?similarity0.
?recommendable0 rdf:type ?someType.
?someType rdfs:subClassOf owbes:Recommendable.
}
It works fine, I get in the results what I'm supposed to. However, I also get the same instance owbes:Dies_Irae. Is there a way to exclude it from the result?
Well, I'm sure there is. I tried to search, I found that there is a filter, I tried to use it, but no succeed. This is the filter that I apply FILTER (?recmmendable0 != owbes:Dies_Irae)
I also tried to check if both of them have the same rdf:about but it didn't work.
Here you go the result:
<http://www.welovethesemanticweb.com/recommendation-systems#Requiem:_Sequentia>
recommendation-systems:hasArtist
"0.4"^^xsd:double .
recommendation-systems:Le_nozze_di_Figaro
recommendation-systems:hasArtist
"0.4"^^xsd:double .
recommendation-systems:Dies_Irae
recommendation-systems:hasArtist
"0.4"^^xsd:double .
as you see, the last instance is the one that I'd like to exclude
FILTER (?recmmendable0 != owbes:Dies_Irae)
You didn't spell recommendable0 correctly in your filter. Since the variable isn't used anywhere else, it never has a value, so the filter doesn't have anything to compare.
I run a Virtuoso Server and missed a number of results when making a SPARQL-Select request. I tracked it down and find a really strange behaviour, that I cannot explain.
But to start from the beginning.
The endpoint I query can be found at http://creativeartefact.org/sparql
I) Check for a specific triple:
ASK WHERE {
<http://creativeartefact.org/mbrainzImport/f18e677a-4051-486a-aa64-d9a3bfef90af>
<http://creativeartefact.org/ontology/represents>
<http://creativeartefact.org/mbrainzImport/35ed9f2a-6ce4-44ca-9c7a-967377b0e007>. }
The query returns TRUE
II) Now getting a bit more unspecific:
ASK WHERE {
?s
<http://creativeartefact.org/ontology/represents>
<http://creativeartefact.org/mbrainzImport/35ed9f2a-6ce4-44ca-9c7a-967377b0e007>. }
If the first returns true, the second shall do as well, shouldn't it? But it doesn't. It return FALSE!
If I replace the predicate or the object with a variable, it returns true as expected. Only when setting a variable for the subject, it returns false.
That the data really exists in the triple store can be tested by running the query
SELECT * WHERE {
?s
?p
<http://creativeartefact.org/mbrainzImport/35ed9f2a-6ce4-44ca-9c7a-967377b0e007>. }
You will see, that both results comw with p = http://creativeartefact.org/ontology/represents - which is exactly the predicate I am asking for in the former query.
To make it even more strange, there ARE triples with the aforementioned format, that return the triples:
select * {
?s
<http://creativeartefact.org/ontology/represents>
<http://creativeartefact.org/mbrainzImport/e4003568-5645-4ee1-abd0-2e8156272e59>. }
Any idea, what is happening here?
Thanks in advance,
Frank
The Virtuoso being used is an original 07.00.3203 build from 2013.
I would suggest upgrading to the latest Virtuoso 07.10.3211, open source or commercial, depending on which is in use here, and see if the problem persists ...