/** Get a graph and direct only the unshielded colliders. */
  public static void basicPattern(Graph graph) {
    Set<Edge> undirectedEdges = new HashSet<Edge>();

    NEXT_EDGE:
    for (Edge edge : graph.getEdges()) {
      Node head = null, tail = null;

      if (edge.getEndpoint1() == Endpoint.ARROW && edge.getEndpoint2() == Endpoint.TAIL) {
        head = edge.getNode1();
        tail = edge.getNode2();
      } else if (edge.getEndpoint2() == Endpoint.ARROW && edge.getEndpoint1() == Endpoint.TAIL) {
        head = edge.getNode2();
        tail = edge.getNode1();
      }

      if (head != null) {
        for (Node node : graph.getParents(head)) {
          if (node != tail && !graph.isAdjacentTo(tail, node)) {
            continue NEXT_EDGE;
          }
        }

        undirectedEdges.add(edge);
      }
    }

    for (Edge nextUndirected : undirectedEdges) {
      Node node1 = nextUndirected.getNode1(), node2 = nextUndirected.getNode2();

      graph.removeEdge(nextUndirected);
      graph.addUndirectedEdge(node1, node2);
    }
  }
Exemplo n.º 2
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  // ===========================SCORING METHODS===================//
  public double scoreDag(Graph graph) {
    Graph dag = new EdgeListGraphSingleConnections(graph);
    buildIndexing(graph);

    double score = 0.0;

    for (Node y : dag.getNodes()) {
      Set<Node> parents = new HashSet<Node>(dag.getParents(y));
      int nextIndex = -1;
      for (int i = 0; i < getVariables().size(); i++) {
        nextIndex = hashIndices.get(variables.get(i));
      }
      int parentIndices[] = new int[parents.size()];
      Iterator<Node> pi = parents.iterator();
      int count = 0;
      while (pi.hasNext()) {
        Node nextParent = pi.next();
        parentIndices[count++] = hashIndices.get(nextParent);
      }

      if (this.isDiscrete()) {
        score += localDiscreteScore(nextIndex, parentIndices);
      } else {
        score += localSemScore(nextIndex, parentIndices);
      }
    }
    return score;
  }
  /**
   * Transforms a maximally directed pattern (PDAG) represented in graph <code>g</code> into an
   * arbitrary DAG by modifying <code>g</code> itself. Based on the algorithm described in
   * Chickering (2002) "Optimal structure identification with greedy search" Journal of Machine
   * Learning Research. R. Silva, June 2004
   */
  public static void pdagToDag(Graph g) {
    Graph p = new EdgeListGraph(g);
    List<Edge> undirectedEdges = new ArrayList<Edge>();

    for (Edge edge : g.getEdges()) {
      if (edge.getEndpoint1() == Endpoint.TAIL
          && edge.getEndpoint2() == Endpoint.TAIL
          && !undirectedEdges.contains(edge)) {
        undirectedEdges.add(edge);
      }
    }
    g.removeEdges(undirectedEdges);
    List<Node> pNodes = p.getNodes();

    do {
      Node x = null;

      for (Node pNode : pNodes) {
        x = pNode;

        if (p.getChildren(x).size() > 0) {
          continue;
        }

        Set<Node> neighbors = new HashSet<Node>();

        for (Edge edge : p.getEdges()) {
          if (edge.getNode1() == x || edge.getNode2() == x) {
            if (edge.getEndpoint1() == Endpoint.TAIL && edge.getEndpoint2() == Endpoint.TAIL) {
              if (edge.getNode1() == x) {
                neighbors.add(edge.getNode2());
              } else {
                neighbors.add(edge.getNode1());
              }
            }
          }
        }
        if (neighbors.size() > 0) {
          Collection<Node> parents = p.getParents(x);
          Set<Node> all = new HashSet<Node>(neighbors);
          all.addAll(parents);
          if (!GraphUtils.isClique(all, p)) {
            continue;
          }
        }

        for (Node neighbor : neighbors) {
          Node node1 = g.getNode(neighbor.getName());
          Node node2 = g.getNode(x.getName());

          g.addDirectedEdge(node1, node2);
        }
        p.removeNode(x);
        break;
      }
      pNodes.remove(x);
    } while (pNodes.size() > 0);
  }
Exemplo n.º 4
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  /** Evaluate the Insert(X, Y, T) operator (Definition 12 from Chickering, 2002). */
  private double insertEval(Node x, Node y, List<Node> t, List<Node> naYX, Graph graph) {
    Set<Node> set1 = new HashSet<Node>(naYX);
    set1.addAll(t);
    List<Node> paY = graph.getParents(y);
    set1.addAll(paY);
    Set<Node> set2 = new HashSet<Node>(set1);
    set1.add(x);

    return scoreGraphChange(y, set1, set2);
  }
Exemplo n.º 5
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  // Can be done concurrently.
  private double deleteEval(Node x, Node y, List<Node> h, List<Node> naYX, Graph graph) {
    List<Node> paY = graph.getParents(y);
    Set<Node> paYMinuxX = new HashSet<Node>(paY);
    paYMinuxX.remove(x);

    Set<Node> set1 = new HashSet<Node>(naYX);
    set1.removeAll(h);
    set1.addAll(paYMinuxX);

    Set<Node> set2 = new HashSet<Node>(naYX);
    set2.removeAll(h);
    set2.addAll(paY);

    return scoreGraphChange(y, set1, set2);
  }