This tutorial will teach you how to create subgraphs. At the end of it, we will have a hierarchy of 3 graphs.

Before anything consider the following function that creates 3 nodes and 3 edges (same as in tutorial 001 ):

void buildGraph(Graph *graph) 
{
  //add three nodes
  node n1=graph->addNode();
  node n2=graph->addNode();
  node n3=graph->addNode();
  //add three edges
  graph->addEdge(n2,n3);
  graph->addEdge(n1,n2);
  graph->addEdge(n3,n1);
}
        	

The creation of a subgraph is quite simple. You just have to use the function Graph* addSubGraph (BooleanProperty* selection = 0) . It will create and return a new SubGraph of the graph. The elements of the new subgraph are those selected in the selection(selection associated value equals true); if there is no selection an empty subgraph is returned.

In the following sample we create 3 empty subgraphs :

  //build three empty subgraphs
  Graph *subgraph0=graph->addSubGraph();
  Graph *subgraph1=graph->addSubGraph();
  Graph *subgraph2=subgraph1->addSubGraph();
        	

We now need to create some nodes and edges :

   //add node inside subgraphs
  buildGraph(subgraph0);
  buildGraph(subgraph1);
  buildGraph(subgraph2);
        	

Following is the hierarchy we have just created, displayed with tulip :

We can check that by iterating on our graph's subgraphs using the function Iterator< Graph * >* Graph::getSubGraphs() :

  //iterate subgraph (0 and 1 normally ) and output them
  Iterator<Graph *> *itS=graph->getSubGraphs();
  while (itS->hasNext())
    cout << itS->next() << endl;
  delete itS;
        	

#include <iostream>
#include <tulip/Graph.h>

/**
 * Tutorial 004
 *
 * Create a graph and three subgraphs,
 * display all the structure using iterators
 */

using namespace std;
using namespace tlp;

void buildGraph(Graph *graph) {
  //add three nodes
  node n1=graph->addNode();
  node n2=graph->addNode();
  node n3=graph->addNode();
  //add three edges
  graph->addEdge(n2,n3);
  graph->addEdge(n1,n2);
  graph->addEdge(n3,n1);
}

int main() {
  //create an empty graph
  Graph *graph=tlp::newGraph();

  //build the graph
  buildGraph(graph);

  //build two empty subgraph
  Graph *subgraph0=graph->addSubGraph();
  Graph *subgraph1=graph->addSubGraph();
  Graph *subgraph2=subgraph1->addSubGraph();

  //add node inside subgraphs
  buildGraph(subgraph0);
  buildGraph(subgraph1);
  buildGraph(subgraph2);

  //iterate subgraph (0 and 1 normally ) and output them
  Iterator<Graph *> *itS=graph->getSubGraphs();
  while (itS->hasNext()) 
    cout << itS->next() << endl;
  delete itS;

  delete graph;
  return EXIT_SUCCESS;
}