You’re right that you can’t use variables in property path expressions. There are a few things that you can do, though, that might help you. A wildcard to check whether a path exists You can use a wildcard by taking the disjunction of it and its negation, so you can do a simple query that … Read more
Your direction was wrong. select distinct * where { ?x dbpedia-owl:wikiPageRedirects <http://dbpedia.org/resource/Paris> }
It might seem a little awkward, but your comment about casting to a string and doing some string-based checks is probably on the right track. You can do it a little bit more efficiently using the SPARQL 1.1 function strstarts: SELECT DISTINCT ?concept WHERE { ?x a ?concept FILTER ( !strstarts(str(?concept), “http://dbpedia.org/class/yago/”) ) } LIMIT … Read more
While you can’t use variables in property paths, you can use a wildcard by taking advantage of the fact that for any URI, every property either is that property or isn’t. E.g., (<>|!<>) matches any property, since every property either is <> or isn’t. You can make a wildcard that goes in either direction by … Read more
Well, the obvious first start is to look at the classes and properties present in the data. Here is how to see what classes are being used: SELECT DISTINCT ?class WHERE { ?s a ?class . } LIMIT 25 OFFSET 0 (LIMIT and OFFSET are there for paging. It is worth getting used to these … Read more
There are two main options for retrieving the data you want. In some cases, it is possible to query the data using a publicly available SPARQL endpoint. This is probably the most convenient approach, and the one to take unless there’s some definite reason that you need the data locally. There are limitations to this … Read more
that is so embarassing, there is space problem in the query: String service = “http://dbpedia.org/sparql”; String queryString = “”; queryString = “PREFIX rdfs: <http://www.w3.org/2000/01/rdf-schema#> SELECT ?label ” + “WHERE {” + “<http://dbpedia.org/resource/Quatre_Bornes> <http://dbpedia.org/ontology/country> ?y .”+ “?y rdfs:label ?label .”+ “FILTER (LANG(?label) = ‘en’)”+ “}”;
While there are some limitations in what property paths can do, depending on your exact requirements, you may be able to get what you need here. Consider this data: @prefix : <urn:ex:>. :a :relatedTo :b . :b :relatedTo :c . :c :relatedTo :d . :a :relatedTo :e . :e :relatedTo :f . :f :relatedTo :g … Read more
This is based on the same technique used to compute the position of an element in an RDF list using SPARQL that is described in: Is it possible to get the position of an element in an RDF Collection in SPARQL? If you have data like this: @prefix : <http://example.org> . :orgA :hasSuborganization :orgB, :orgC, … Read more
You can GROUP BY by the variables that identify the tweet and then use GROUP_CONCAT to concatenate the hashtags into something like an array, but it will still be a string that you’ll need to parse afterward. For instance, given data like @prefix smo: <http://example.org/> . @prefix : <http://example.org/> . :tweet1 smo:tweeted_at “1” ; smo:has_hashtag … Read more