private void init(Graph<V, E> g, Set<V> vertexSet, Set<E> edgeSet) {
    // create a map between vertex value to its order(1st,2nd,etc)
    // "CAT"=1 "DOG"=2 "RHINO"=3

    this.mapVertexToOrder = new HashMap<V, Integer>(vertexSet.size());

    int counter = 0;
    for (V vertex : vertexSet) {
      mapVertexToOrder.put(vertex, new Integer(counter));
      counter++;
    }

    // create a friendlier representation of an edge
    // by order, like 2nd->3rd instead of B->A
    // use the map to convert vertex to order
    // on directed graph, edge A->B must be (A,B)
    // on undirected graph, edge A-B can be (A,B) or (B,A)

    this.labelsEdgesSet = new HashSet<LabelsEdge>(edgeSet.size());
    for (E edge : edgeSet) {
      V sourceVertex = g.getEdgeSource(edge);
      Integer sourceOrder = mapVertexToOrder.get(sourceVertex);
      int sourceLabel = sourceOrder.intValue();
      int targetLabel = (mapVertexToOrder.get(g.getEdgeTarget(edge))).intValue();

      LabelsEdge lablesEdge = new LabelsEdge(sourceLabel, targetLabel);
      this.labelsEdgesSet.add(lablesEdge);

      if (g instanceof UndirectedGraph<?, ?>) {
        LabelsEdge oppositeEdge = new LabelsEdge(targetLabel, sourceLabel);
        this.labelsEdgesSet.add(oppositeEdge);
      }
    }
  }
  /**
   * Compute the unique decomposition of the input graph G (atoms of G). Implementation of algorithm
   * Atoms as described in Berry et al. (2010), DOI:10.3390/a3020197, <a
   * href="http://www.mdpi.com/1999-4893/3/2/197">http://www.mdpi.com/1999-4893/3/2/197</a>
   */
  private void computeAtoms() {
    if (chordalGraph == null) {
      computeMinimalTriangulation();
    }

    separators = new HashSet<>();

    // initialize g' as subgraph of graph (same vertices and edges)
    UndirectedGraph<V, E> gprime = copyAsSimpleGraph(graph);

    // initialize h' as subgraph of chordalGraph (same vertices and edges)
    UndirectedGraph<V, E> hprime = copyAsSimpleGraph(chordalGraph);

    atoms = new HashSet<>();

    Iterator<V> iterator = meo.descendingIterator();
    while (iterator.hasNext()) {
      V v = iterator.next();
      if (generators.contains(v)) {
        Set<V> separator = new HashSet<>(Graphs.neighborListOf(hprime, v));

        if (isClique(graph, separator)) {
          if (separator.size() > 0) {
            if (separators.contains(separator)) {
              fullComponentCount.put(separator, fullComponentCount.get(separator) + 1);
            } else {
              fullComponentCount.put(separator, 2);
              separators.add(separator);
            }
          }
          UndirectedGraph<V, E> tmpGraph = copyAsSimpleGraph(gprime);

          tmpGraph.removeAllVertices(separator);
          ConnectivityInspector<V, E> con = new ConnectivityInspector<>(tmpGraph);
          if (con.isGraphConnected()) {
            throw new RuntimeException("separator did not separate the graph");
          }
          for (Set<V> component : con.connectedSets()) {
            if (component.contains(v)) {
              gprime.removeAllVertices(component);
              component.addAll(separator);
              atoms.add(new HashSet<>(component));
              assert (component.size() > 0);
              break;
            }
          }
        }
      }

      hprime.removeVertex(v);
    }

    if (gprime.vertexSet().size() > 0) {
      atoms.add(new HashSet<>(gprime.vertexSet()));
    }
  }
Esempio n. 3
0
  /**
   * Finds the vertex set for the subgraph of all cycles.
   *
   * @return set of all vertices which participate in at least one cycle in this graph
   */
  public Set<V> findCycles() {
    // ProbeIterator can't be used to handle this case,
    // so use StrongConnectivityInspector instead.
    StrongConnectivityInspector<V, E> inspector = new StrongConnectivityInspector<V, E>(graph);
    List<Set<V>> components = inspector.stronglyConnectedSets();

    // A vertex participates in a cycle if either of the following is
    // true:  (a) it is in a component whose size is greater than 1
    // or (b) it is a self-loop

    Set<V> set = new HashSet<V>();
    for (Set<V> component : components) {
      if (component.size() > 1) {
        // cycle
        set.addAll(component);
      } else {
        V v = component.iterator().next();
        if (graph.containsEdge(v, v)) {
          // self-loop
          set.add(v);
        }
      }
    }

    return set;
  }
Esempio n. 4
0
  /**
   * @param vertexNumber the number which identifies the vertex v in this order.
   * @return the identifying numbers of all vertices which are connected to v by an edge incoming to
   *     v.
   */
  public int[] getInEdges(int vertexNumber) {
    if (cacheEdges && (incomingEdges[vertexNumber] != null)) {
      return incomingEdges[vertexNumber];
    }

    V v = getVertex(vertexNumber);
    Set<E> edgeSet;

    if (graph instanceof DirectedGraph<?, ?>) {
      edgeSet = ((DirectedGraph<V, E>) graph).incomingEdgesOf(v);
    } else {
      edgeSet = graph.edgesOf(v);
    }

    int[] vertexArray = new int[edgeSet.size()];
    int i = 0;

    for (E edge : edgeSet) {
      V source = graph.getEdgeSource(edge), target = graph.getEdgeTarget(edge);
      vertexArray[i++] = mapVertexToOrder.get(source.equals(v) ? target : source);
    }

    if (cacheEdges) {
      incomingEdges[vertexNumber] = vertexArray;
    }

    return vertexArray;
  }
 /**
  * .
  *
  * @return
  */
 public int edgeCount() {
   return vertexEdges.size();
 }
 public int outDegreeOf(V vertex) {
   Set<E> res = outgoingEdgesOf(vertex);
   return res.size();
 }
 public int inDegreeOf(V vertex) {
   Set<E> res = incomingEdgesOf(vertex);
   return res.size();
 }