Class: TaliaUtil::RdfUpdate

Inherits:
Object show all
Defined in:
lib/talia_util/rdf_update.rb

Overview

Some methods to update the RDF store. There is no real inferencing, just some hardcoded rules that help to provide basic functionality with simple RDF stores.

Class Method Summary collapse

Class Method Details

.owl_to_rdfs ⇒ Object

This is the wrapper for rdfs_from_owl for the rake task



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# File 'lib/talia_util/rdf_update.rb', line 11

def owl_to_rdfs
  puts "Checking for OWL classes."
  # Register the namespaces for ActiveRDF
  ActiveRDF::Namespace.register(:rdfs, N::RDFS.to_s)
  ActiveRDF::Namespace.register(:owl, N::OWL.to_s)
  progress = nil
  size, modified, blanks = rdfs_from_owl do |size|
    progress ||= begin
      puts "#{size} OWL classes found, adding rdfs:Class type for each."
      ProgressBar.new("Updating RDF database", size)
    end
    progress.inc
  end
  
  progress.finish if(progress)
  puts "Finished updating. Updated #{modified} of #{size} classes. #{blanks} blank nodes were ignored."
  
end

.rdfs_from_owl ⇒ Object

This checks for owl:Classes and adds and rdfs:Class triple to them. This doesn’t check if the triple already exists, and thus may cause duplicates. You can pass a block that will be called with the overall size as a parameter.

It returns the overall size, the number of modified elements and the number of blank nodes



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# File 'lib/talia_util/rdf_update.rb', line 37

def rdfs_from_owl
  # Remove previous auto rdfs triples
  ActiveRDF::FederationManager.clear(N::TALIA.auto_rdfs.context)
  
  # This gets all OWL classes in the store
  all_qry = ActiveRDF::Query.new(N::URI).distinct.select(:class)
  all_qry.where(:class, N::RDF::type, N::OWL.Class)
  all_owl = all_qry.execute
  
  # This gets all OWL classes that already have an RDF class attached
  qry_rdfs = ActiveRDF::Query.new(N::URI).distinct.select(:class)
  qry_rdfs.where(:class, N::RDF::type, N::OWL.Class)
  qry_rdfs.where(:class, N::RDF::type, N::RDFS.Class)
  classes_with_rdfs = qry_rdfs.execute
  
  
  modified = 0
  blanks = 0
  
  class_hash = {}
  
  # Put all the existing owl classes in a hash
  all_owl.each do |owl_class|
    if(owl_class.is_a?(RDFS::BNode))
      blanks = blanks + 1
      next
    end
    
    class_hash[owl_class] = :has_rdfs_class
  end
  
  # Now remove the ones that already have an RDF class
  classes_with_rdfs.each do |owl_class|
    next if(owl_class.is_a?(RDFS::BNode))
    
    class_hash[owl_class] = :no_rdfs_class
  end
  
  # Now go through all klasses and add the missing triples
  class_hash.each do |klass, status|
    if(status == :has_rdfs_class)
      modified = modified + 1
      ActiveRDF::FederationManager.add(N::URI.new(klass), N::RDF.type, N::RDFS.Class, N::TALIA.auto_rdfs_context)
    end
    yield(class_hash.size) if(block_given?)
  end
  
  return [class_hash.size, modified, blanks]
end