I am querying marine data via SPARQL. I developed a SPARQL console with CodeMirror, RDFLib and SPARQLWrapper in order to display a number of predefined queries and results in my website. In the console, the query:
prefix geo: <https://www.w3.org/2003/01/geo/wgs84_pos#>
prefix owl: <http://www.w3.org/2002/07/owl#>
prefix rdf: <http://www.w3.org/1999/02/22-rdf-syntax-ns#>
prefix ssn: <http://www.w3.org/ns/ssn/>
prefix xml: <http://www.w3.org/XML/1998/namespace>
prefix xsd: <http://www.w3.org/2001/XMLSchema#>
prefix argo: <http://www.argodatamgt.org/argo-ontology#>
prefix foaf: <http://xmlns.com/foaf/0.1/>
prefix rdfs: <http://www.w3.org/2000/01/rdf-schema#>
prefix sosa: <http://www.w3.org/ns/sosa/>
prefix nerc: <http://vocab.nerc.ac.uk/collection/>
prefix dct: <http://purl.org/dc/terms/>
prefix prov: <https://www.w3.org/TR/prov-o/>
# stations/date of each cycle
SELECT distinct ?wmo ?lat ?lon ?date where{
?float argo:cycle ?cycle;
argo:wmoCode ?wmo.
?cycle geo:latitude ?lat;
geo:longitude ?lon;
argo:startDate ?date.
}
returns nothing. I cross-checked it by using https://www.orpha.net/sparql , a query editor, and the result was the same - empty result set.
However, when I try the exact same query in the research infrastructure's SPARQL Endpoint https://www.ifremer.fr/co/argo-linked-data/html/Argo-HTML-SPARQL/ , it works flawlessly.
I have tried very generic queries like:
SELECT DISTINCT * WHERE {
?s ?p ?o
}
LIMIT 10
or
select distinct ?p ?label
where {
?s ?p ?o .
OPTIONAL { ?p rdfs:label ?label }
}
and they return non-empty results both in my console and in the generic SPARQL editor I mentioned before.
Performing a CURL request, modifying the template query by the first mentioned "stations/date of each cycle" one I am able to get the data:
curl -X POST "https://sparql.ifremer.fr/argo/query" --data-urlencode "query=select ?s ?o ?p where{?s ?o ?p.} limit 10"
This makes me think that an outdated Virtuoso server on their side might be the culprit, however, I am very new in SPARQL and Semantics to tell and I would appreciate any clue.
As OP said in comment --
I found the culprit and it was an error from my side. I am using SPARQLWrapper and somewhere in my code I had a fixed SPARQL endpoint from another research infrastructure, I totally missed that.
Related
I have a list of artstyles in graphDB, i am trying to use the SERVICE function to get their labels from Wikidata with this query:
PREFIX gp: <http://www.semanticweb.org/kandd/group76/final_project#>
PREFIX rdfs: <http://www.w3.org/2000/01/rdf-schema#>
SELECT ?movement ?label
WHERE{
?artist gp:hasArtStyle ?movement.
SERVICE <https://query.wikidata.org/sparql>{
?movement rdfs:label ?label .
FILTER (langMatches( lang(?label), "EN" ) )
}
}
note that gp is a namespace that only exists in my graph, not anywhere on the internet and also note that ?movement contains a list of valid Wikidata URIs such as http://www.wikidata.org/entity/Q186030
yet still the response I get is:
Error 500: error
Query evaluation error: org.eclipse.rdf4j.query.QueryEvaluationException: org.eclipse.rdf4j.query.QueryEvaluationException: java.io.IOException: Unkown record type: 83 (HTTP status 500)
What am I doing wrong?
Remember that you query is handled from the inside to the outside, meaning that the service part is handled first, and then the part where you use your own specific property.
Currently, your query on WikiData is very general. You ask for everything that has a rdfs:label, and then filter on all the English labels it returns.
Given this, my guess is that you query simply times out. Instead, I would try something like this:
PREFIX rdfs: <http://www.w3.org/2000/01/rdf-schema#>
PREFIX wdt: <http://www.wikidata.org/prop/direct/>
PREFIX wd: <http://www.wikidata.org/entity/>
SELECT *
WHERE{
SERVICE <https://query.wikidata.org/sparql>{
?artist wdt:P101 wd:Q186030 ; #Field of Work is contemporary art
wdt:P31 wd:Q5 ; #instance of Human
rdfs:label ?name . #get the label
FILTER (langmatches(lang(?name), "en"))
}
}
If I try this in GraphDB, it returns 156 results.
I am querying an ontology on the Bioportal endpoint. The ontology (NIF) is stored as a graph, so I put it in the FROM clause as the endpoint instructed.
SELECT DISTINCT ?p
FROM <http://bioportal.bioontology.org/ontologies/NIF>
WHERE{
?p a rdf:Property
}
limit 100
However, as can be seen below, the results came back showing few properties related to NIF and others to a different ontology called SKOS (Simple Knowledge Organization System).
In the Bioportal documentation it is said it maps some properties to SKOS properties, so I thought maybe the results are fine.
However, I had to test if I am querying the correct graph. So I used the below code to count the number of nodes since I know the NIF has around 3.6 million triples!
SELECT (count (*) as ?nodes)
FROM <http://bioportal.bioontology.org/ontologies/NIF>
WHERE{
?s ?p ?o
}
This resulted in 7984 nodes with and without the FROM clause! So I guessed I should be using the "count" incorrectly!
So I wonder how I should make sure that I am just querying the NIF ontology. Also, how to count its nodes?
Thanks :)
Try using SERVICE keyword.
PREFIX rdf: <http://www.w3.org/1999/02/22-rdf-syntax-ns#>
PREFIX rdfs: <http://www.w3.org/2000/01/rdf-schema#>
SELECT (count (*) as ?nodes)
WHERE
{
SERVICE <http://bioportal.bioontology.org/ontologies/NIF>
{
?s ?p ?o
}
}
If this fails, possibly the service you are connecting is not correct or up.
Try below example which connects to DBpedia:
PREFIX rdf: <http://www.w3.org/1999/02/22-rdf-syntax-ns#>
PREFIX rdfs: <http://www.w3.org/2000/01/rdf-schema#>
SELECT (count (*) as ?nodes)
WHERE
{
SERVICE <http://DBpedia.org/sparql>
{
?s ?p ?o
}
}
By the way I can;t access URL http://bioportal.bioontology.org/ontologies/NIF. Seems to be unavailable or down.
This is an evolution of this question.
Basically I am having trouble getting all the solutions to a SPARQL query from a remote endpoint. I have read through section 2.4 here because it seems to describe a situation almost identical to mine.
The idea is that I want to filter my results from DBPedia based on information in my local RDF graph. The query is here:
PREFIX ns1:
<http://www.semanticweb.org/caeleanb/ontologies/twittermap#>
PREFIX dbo: <http://dbpedia.org/ontology/>
SELECT *
WHERE {
?p ns1:displayName ?name .
SERVICE <http://dbpedia.org/sparql> {
?s rdfs:label ?name .
?s rdf:type foaf:Person .
}
}
And the only result I get is dbpedia:John_McCain (for ?s). I think this is because John McCain is the only match in the first 'x' results, but I can't figure out how to get the query to return all matches. For example, if I add a filter like:
SERVICE <http://dbpedia.org/sparql> {
?s rdfs:label ?name .
?s rdf:type foaf:Person .
FILTER(?name = "John McCain"#en || ?name = "Jamie Oliver"#en)
}
Then it correctly returns BOTH dbpedia:Jamie_Oliver and dbpedia:John_McCain. There are dozens of other matches like Jamie Oliver that do not come through unless I specifically add it to a Filter like this.
Can someone explain a way to extract the rest of the matches? Thanks.
It looks like the cause of this issue is that the SERVICE block is attempting to pull all foaf:Persons from DBPedia, and then filter them based on my local Stardog db. Since there is a 10,000 result limit when querying DBPedia, only matches which occur in that set of 10,000 arbitrary Persons will be found. To fix this, I wrote a script to put together a FILTER block containing every string name in my Stardog db and attached it to the SERVICE block to filter remotely and thereby avoid hitting the 10,000 result limit. It looks something like this:
PREFIX rdf: <http://www.w3.org/1999/02/22-rdf-syntax-ns#>
PREFIX dbo: <http://dbpedia.org/ontology/>
PREFIX dbr: <http://dbpedia.org/resource/>
PREFIX foaf: <http://xmlns.com/foaf/0.1/>
PREFIX rdfs: <http://www.w3.org/2000/01/rdf-schema#>
PREFIX dbo: <http://dbpedia.org/ontology/>
PREFIX ns1: <http://www.semanticweb.org/caeleanb/ontologies/twittermap#>
CONSTRUCT{
?s rdf:type ns1:Person ;
ns1:Politician .
}
WHERE {
?s rdfs:label ?name .
?s rdf:type dbo:Politician .
FILTER(?name IN ("John McCain"#en, ...)
}
I am new to RDF, so it will be very nice if you can help me with this!
I am trying to query the subject of pickles called "Umeboshi"(It is japanese pickles) as follows:
PREFIX rdfs: <http://www.w3.org/2000/01/rdf-schema#>
PREFIX type: <http://dbpedia.org/class/yago/>
PREFIX prop: <http://dbpedia.org/property/>
PREFIX onto: <http://dbpedia.org/ontology/>
SELECT ?label ?subject
WHERE {
?Thing
rdfs:label ?label;
prop:subject?subject.
FILTER (?label = "Umeboshi")
}
This query doesn't give me any data.
As I don't know where to find available properties I am referring to the Umeboshi page on dbpedia http://live.dbpedia.org/page/Umeboshi.
Thank you very much for your help!
Two things I found:
In the page you give, the label is given in English, but in your query you omit the language.
subject has a different namespace. It is a dcterm concept and not a dbpedia property.
This leads to the following, changed query, which results in three bindings:
PREFIX rdfs: <http://www.w3.org/2000/01/rdf-schema#>
PREFIX dct: <http://purl.org/dc/terms/>
SELECT ?label ?subject
WHERE {
?Thing
rdfs:label ?label;
dct:subject ?subject.
FILTER (?label = "Umeboshi"#en)
}
I have this query
PREFIX rdf: <http://www.w3.org/1999/02/22-rdf-syntax-ns#>
PREFIX rdfs: <http://www.w3.org/2000/01/rdf-schema#>
PREFIX foaf: <http://xmlns.com/foaf/0.1/>
PREFIX dbpedia: <http://dbpedia.org/>
PREFIX dbpedia_property: <http://dbpedia.org/property/>
PREFIX dbpedia_ontology: <http://dbpedia.org/ontology/>
PREFIX yago: <http://dbpedia.org/class/yago/>
PREFIX schema: <http://schema.org/>
SELECT * WHERE
{
{
SELECT ?school
WHERE
{
?school rdf:type yago:EducationalInstitution108276342 .
FILTER ( contains(str(?school), "Australia") )
}
ORDER BY ?school
}
}
Don't mind the extra brackets as this is part of a larger query.
What I want to know is why thi http://dbpedia.org/page/Academic_structure_of_the_Australian_National_University is included in the results since I specify rdf:type yago:EducationalInstitution108276342. This property is not included in the resource page. I'm using this endpoint: http://dbpedia.org/sparql
Looks like a bug in the Pubby Web interface or in the query that is used to get the data that will be shown.
The query
SELECT * WHERE{
<http://dbpedia.org/resource/Academic_Structure_of_the_Australian_National_University> ?p ?o
}
returns the necessary rdf:type statement.
The other strange thing is that even a SPARQL DESCRIBE query does not return the rdd:type triples:
DESCRIBE <http://dbpedia.org/resource/Academic_Structure_of_the_Australian_National_University>
Although DESCIBE is not really defined in the specs, a user would expect those triples for sure. And maybe this kind of query is used to retrieve the data for the Web pages of resources.