I am trying to fetch a list of American movies adapted from books from dbpedia. This is what I have so far:
PREFIX onto: <http://dbpedia.org/ontology/>
PREFIX dcterms: <http://purl.org/dc/terms/>
SELECT * WHERE {
?movie dcterms:subject <http://dbpedia.org/resource/Category:American_films> .
?movie dcterms:subject <http://dbpedia.org/resource/Category:Films_based_on_novels> .
?movie onto:basedOn ?book .
?book a onto:Book .
}
I get only 4 results back. Is there another property I can use to get more results?
First thing, try removing the second line of your pattern --
?movie dcterms:subject <http://dbpedia.org/resource/Category:Films_based_on_novels> .
You'll get a great many more results from --
PREFIX onto: <http://dbpedia.org/ontology/>
PREFIX dcterms: <http://purl.org/dc/terms/>
SELECT * WHERE
{
?movie dcterms:subject <http://dbpedia.org/resource/Category:American_films> ;
onto:basedOn ?book .
?book a onto:Book .
}
Have you looked at the descriptions of the results you did get? That will show you the properties you might use...
Remember that you're limited by the data in DBpedia, which may not have what you think it should (for instance, not every film based on a novel is explicitly categorized as such, as you can see by the different results I got), and may also be 6 or more months out of sync with Wikipedia. You might look at DBpedia-live, for constantly updated ingestion.
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.
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 trying to retrieve the publication date and the no.of pages for books in DBpedia. I tried the following query and it gives empty results. I see that these are properties under book(http://mappings.dbpedia.org/server/ontology/classes/Book) but could not retrieve it.
I would like to know if there is an error in the code or if dbpedia does not store these dates related to books.
SELECT ?book ?genre ?date ?numberOfPages
WHERE {
?book rdf:type dbpedia-owl:Book .
?book dbp:genre ?genre .
?book dbp:firstPublicationDate ?date .
OPTIONAL {?book dbp:numberOfPages ?numberOfPages .}
}
The dbp:firstPublicationDate does not work for two reasons:
First, as pointed in the first answer, you used the wrong prefix.
But even if you correct it, you'll see that you would still have no results. Then the best thing to do is to test with the minimum number of patters, in you case you should as for books with first publication date, two triple pattern only. If you still don't get results, you should test how <http://dbpedia.org/ontology/firstPublicationDate> is actually used with a query like this:
SELECT ?class (COUNT (DISTINCT ?s) AS ?instances)
WHERE {
?s <http://dbpedia.org/ontology/firstPublicationDate> ?date ;
a ?class
}
GROUP BY ?class
ORDER BY DESC(?instances)
LIMIT 1000
Mapping based properties are using the namespace http://dbpedia.org/ontology/, thus, the prefix must be dbo instead of dbp, which stands for http://dbpedia.org/property/.
PREFIX dbo: <http://dbpedia.org/ontology/>
PREFIX dbp: <http://dbpedia.org/property/>
SELECT ?book ?genre ?date ?numberOfPages
WHERE {
?book a dbo:Book ;
dbp:genre ?genre ;
dbo:firstPublicationDate ?date .
OPTIONAL {?book dbp:numberOfPages ?numberOfPages .}
}
Some additional comments:
put the prefixes to the SPARQL query such that others here can run it without any exceptions (also in the future) - the current SPARQL query uses dbpedia-owl but this one is not pre-defined on the official DBpedia anymore - it's called dbo instead
which brings me to the second point -> if you're using a public SPARQL endpoint, show its URL
you can start debugging your own SPARQL query by simply starting with only parts of it and adding more triple patterns then, e.g. in your case you could check if there is any triple with the property with
PREFIX dbp: <http://dbpedia.org/property/>
SELECT * WHERE {?book dbp:firstPublicationDate ?date } LIMIT 10
Update
As Ivo Velitchkov noticed in his answer below, the property dbo:firstPublicationDate is only used for mangas, etc., i.e. written work that was published periodically. Thus, the result will be empty.
I need to get the co-ordinates of some particular places from DbPedia. For the same I am using following snippet:
PREFIX geo: <http://www.w3.org/2003/01/geo/wgs84_pos#>
PREFIX dbo: <http://dbpedia.org/ontology/>
PREFIX foaf: <http://xmlns.com/foaf/0.1/>
SELECT * WHERE {
?x foaf:name 'Mumbai'.
?x dbo:Place 'Mumbai'.
?x geo:lat ?lat .
?x geo:long ?long .
}
On running at http://dbpedia.org/sparql, it returns an empty page. I think I didn't put the name of place in the correct way. Can anyone help me to find the issue
Have a look at the N3/TTL serialization of the data for Mumbai. Note that the foaf:name value has a language tag: foaf:name "Mumbai"#en. You need to use "Mumbai"#en, with the language tag, in the query. Additionally, doing dbo:Place 'Mumbai' doesn't make any sense. You might instead want to ask for things which are dbpedia-owl:Places. You'd end up with a query like:
select * {
?mumbai a dbpedia-owl:Place ;
foaf:name "Mumbai"#en ;
geo:lat ?lat ;
geo:long ?long
}
SPARQL Results
All, I'm trying to get a director's filmography from dbpedia:
Both the queries below (and other attempts not shown) return empty sets. Query below doesn't work:
PREFIX d: <http://dbpedia.org/ontology/>
SELECT ?filmName WHERE {
?film d:director :woody_allen .
?film rdfs:label ?filmName .
}
Or (this is from) :
PREFIX m: <http://data.linkedmdb.org/resource/movie/>
PREFIX rdfs: <http://www.w3.org/2000/01/rdf-schema#>
SELECT ?filmTitle WHERE {
?film rdfs:label ?filmTitle.
?film m:director ?dir.
?dir m:director_name "Sofia Coppola".
}
Not sure what would be the problem with such simple queries. Any ideas here?
The problem with your first query is the use of :woody_allen (besides the fact that you haven't actually defined the default prefix and so the query should technically be illegal SPARQL) the term doesn't actually appear in the data as written.
Try rewriting your query like so:
PREFIX d: <http://dbpedia.org/ontology/>
SELECT ?filmName WHERE {
?film d:director <http://dbpedia.org/resource/Woody_Allen> .
?film rdfs:label ?filmName .
}
The above does give results.
As for your second query DBPedia does not use the Linked MDB ontologies so that query can't match anything