code: function getSubjectBarycenter(subject){
  
  	var weighted_number_of_edges = 0;
  	var number_of_edges = 0;
  	for( var o = 1; o <= object_vector.length; o++ ){
  	    if( relation_matrix[object_vector[o -1].id()] &&
  		relation_matrix[object_vector[o -1].id()][subject.id()]){
  		weighted_number_of_edges += o;
  		number_of_edges++;
  	    }
  	}
  	// The '-1' is to offset the indexing.
  	return ( weighted_number_of_edges / number_of_edges ) -1;
      }
docs: Gets barycenter for column s.