Extracting RDF subgraphs using SPARQL

extract-subgraph-3levels.rq

# this query extracts a subgraph from the selected subject (level 1) and two child levels
PREFIX aekos: <http://www.aekos.org.au/ontology/1.0.0#>
PREFIX some_dataset: <http://www.aekos.org.au/ontology/1.0.0/some_dataset#>

CONSTRUCT {
  ?s1 ?p1 ?o1 .
  ?s1 ?pv1 ?v1 .
  ?s2 ?p2 ?o2 .
  ?s2 ?pv2 ?v2 .
  ?s3 ?p3 ?o3 .
  ?s3 ?pv3 ?v3 .
}
FROM wadec_ravensthorpe:
WHERE {
  # level 1
  ?s1 ?p1 ?o1 FILTER (?s1 = some_dataset:ENTITY-123) . # identify starting subject
  ?s1 ?pv1 ?v1 .
  BIND (?o1 as ?s2) . # rename binding for readability
  # level 2
  ?s2 ?p2 ?o2 . # get links to other subjects
  ?s2 ?pv2 ?v2 . # get primitives
  BIND (?o2 as ?s3) .
  # level 3
  ?s3 ?p3 ?o3 .
  ?s3 ?pv3 ?v3 .
}

extract-subgraph-all-levels.rq

# this query extracts a subgraph from the selected subject (level 1) until no more paths can be traversed
# BEWARE: you're traversing a *graph*, not a tree, so if you have cycles then this query will never finish.
PREFIX aekos: <http://www.aekos.org.au/ontology/1.0.0#>
PREFIX some_dataset: <http://www.aekos.org.au/ontology/1.0.0/some_dataset#>

CONSTRUCT {
  ?s1 ?p1 ?o1 .
  ?sN ?pN ?oN .
}
FROM some_dataset:
WHERE {
  ?s1 ?p1 ?o1 . # level 1
  values ?s1 {
    some_dataset:ENTITY-123 # identify starting subject
  }
  BIND (?o1 as ?s2) . # rename binding for readability
  ?s2 (!<urn:nothing>)+ [] . # any length property path where the property != "something it will never equal" (i.e. find everything)
  ?sN ?pN ?oN . # bind everything
}