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sparqlrdf

SPARQL query to get a node sub graph at n level depth

I am looking to get a sub graph of a given node to a given k level of depth as shown in the following image for k=2.

enter image description here

If I go to https://dbpedia.org/sparql and select a ?city I want to get all the details of the city graph to say 5 levels. I am looking for a generic query that do not need to have knowledge of the graph to fetch the data like below.

CONSTRUCT {
  ?city a ?plebs .
  ?mayor foaf:gender ?gender.
  ?city dbo:country ?ctr .
  ?city dbo:populationTotal ?pop.
  ?city dbo:leaderParty ?party .
  ?city rdfs:label ?cityName .
  ?party dbo:ideology ?ideology 
} WHERE {
   ?plebs rdfs:subClassOf dbo:Settlement.
   ?city a ?plebs .
   ?city (dbp:mayor | dbo:mayor | dbp:leader |dbo:leader | dbo:leaderName) ?mayor .
   ?mayor foaf:gender ?gender.
   ?city dbo:populationTotal ?pop .
   ?city rdfs:label ?cityName .
   ?city dbo:country ?ctr .
   ?city dbo:leaderParty ?party .
   ?party dbo:ideology ?ideology .
   FILTER(str(?gender) = "female")
  }
ORDER BY DESC(?pop)

How can I write a generic SPARQL query that can work on any database for a given node?

Solution

  • It's actually pretty easy:

    construct {

?s ?p ?o.
?o ?op ?oo.
?oo ?oop ?ooo.
?ooo ?ooop ?oooo.
?oooo ?oooop ?ooooo.
}
where {
bind(city:_London as ?s)
?s ?p ?o.
optional {
   ?o ?op ?oo.
   optional {
      ?oo ?oop ?ooo.
       optional {
          ?ooo ?ooop ?oooo.
          optional {
              ?oooo ?oooop ?ooooo.
           }
        }
     }
  }
}

    The construct statement will return the graph of all outbound links from the city in question, and any time you have a null returned, that triple will simply not be constructed.