Esempio n. 1
0
  // ===========================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;
  }
Esempio n. 2
0
  private Graph changeLatentNames(Graph full, Clusters measurements, List<String> latentVarList) {
    Graph g2 = null;

    try {
      g2 = (Graph) new MarshalledObject(full).get();
    } catch (IOException e) {
      e.printStackTrace();
    } catch (ClassNotFoundException e) {
      e.printStackTrace();
    }

    for (int i = 0; i < measurements.getNumClusters(); i++) {
      List<String> d = measurements.getCluster(i);
      String latentName = latentVarList.get(i);

      for (Node node : full.getNodes()) {
        if (!(node.getNodeType() == NodeType.LATENT)) {
          continue;
        }

        List<Node> _children = full.getChildren(node);

        _children.removeAll(ReidentifyVariables.getLatents(full));

        List<String> childNames = getNames(_children);

        if (new HashSet<String>(childNames).equals(new HashSet<String>(d))) {
          g2.getNode(node.getName()).setName(latentName);
        }
      }
    }

    return g2;
  }
Esempio n. 3
0
  private boolean existsUnblockedSemiDirectedPath(Node from, Node to, List<Node> cond, Graph G) {
    Queue<Node> Q = new LinkedList<Node>();
    Set<Node> V = new HashSet<Node>();
    Q.offer(from);
    V.add(from);

    while (!Q.isEmpty()) {
      Node t = Q.remove();
      if (t == to) return true;

      for (Node u : G.getAdjacentNodes(t)) {
        Edge edge = G.getEdge(t, u);
        Node c = Edges.traverseSemiDirected(t, edge);
        if (c == null) continue;
        if (cond.contains(c)) continue;
        if (c == to) return true;

        if (!V.contains(c)) {
          V.add(c);
          Q.offer(c);
        }
      }
    }

    return false;
  }
Esempio n. 4
0
  private Graph restrictToEmpiricalLatents(Graph mimStructure, Graph mimbuildStructure) {
    Graph _mim = new EdgeListGraph(mimStructure);

    for (Node node : mimbuildStructure.getNodes()) {
      if (!mimbuildStructure.containsNode(node)) {
        _mim.removeNode(node);
      }
    }

    return _mim;
  }
Esempio n. 5
0
  private Graph structure(Graph mim) {
    List<Node> latents = new ArrayList<Node>();

    for (Node node : mim.getNodes()) {
      if (node.getNodeType() == NodeType.LATENT) {
        latents.add(node);
      }
    }

    return mim.subgraph(latents);
  }
Esempio n. 6
0
  // Cannot be done if the graph changes.
  public void setInitialGraph(Graph initialGraph) {
    initialGraph = GraphUtils.replaceNodes(initialGraph, variables);

    out.println("Initial graph variables: " + initialGraph.getNodes());
    out.println("Data set variables: " + variables);

    if (!new HashSet<Node>(initialGraph.getNodes()).equals(new HashSet<Node>(variables))) {
      throw new IllegalArgumentException("Variables aren't the same.");
    }

    this.initialGraph = initialGraph;
  }
Esempio n. 7
0
  private void uncorrelationExogenousVariables() {
    Graph graph = getWorkbench().getGraph();

    Set<Edge> edges = graph.getEdges();

    for (Edge edge : edges) {
      if (Edges.isBidirectedEdge(edge)) {
        try {
          graph.removeEdge(edge);
        } catch (Exception e) {
          // Ignore.
        }
      }
    }
  }
Esempio n. 8
0
  /**
   * Forward equivalence search.
   *
   * @param graph The graph in the state prior to the forward equivalence search.
   */
  private void fes(Graph graph, List<Node> nodes) {
    TetradLogger.getInstance().log("info", "** FORWARD EQUIVALENCE SEARCH");

    lookupArrows = new HashMap<OrderedPair, Set<Arrow>>();

    initializeArrowsForward(nodes);

    while (!sortedArrows.isEmpty()) {
      Arrow arrow = sortedArrows.first();
      sortedArrows.remove(arrow);

      Node x = arrow.getX();
      Node y = arrow.getY();

      clearArrow(x, y);

      if (graph.isAdjacentTo(x, y)) {
        continue;
      }

      if (!validInsert(x, y, arrow.getHOrT(), arrow.getNaYX(), graph)) {
        continue;
      }

      List<Node> t = arrow.getHOrT();
      double bump = arrow.getBump();

      Set<Edge> edges = graph.getEdges();

      insert(x, y, t, graph, bump);
      score += bump;
      rebuildPattern(graph);

      // Try to avoid duplicating scoring calls. First clear out all of the edges that need to be
      // changed,
      // then change them, checking to see if they're already been changed. I know, roundabout, but
      // there's
      // a performance boost.
      for (Edge edge : graph.getEdges()) {
        if (!edges.contains(edge)) {
          reevaluateForward(graph, nodes, edge.getNode1(), edge.getNode2());
        }
      }

      storeGraph(graph);
    }
  }
Esempio n. 9
0
  /** 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);
  }
Esempio n. 10
0
  /** Returns true iif the given set forms a clique in the given graph. */
  private static boolean isClique(List<Node> nodes, Graph graph) {
    for (int i = 0; i < nodes.size() - 1; i++) {
      for (int j = i + 1; j < nodes.size(); j++) {
        if (!graph.isAdjacentTo(nodes.get(i), nodes.get(j))) {
          return false;
        }
      }
    }

    return true;
  }
Esempio n. 11
0
  /**
   * Find all nodes that are connected to Y by an undirected edge that are adjacent to X (that is,
   * by undirected or directed edge).
   */
  private static List<Node> getNaYX(Node x, Node y, Graph graph) {
    List<Edge> yEdges = graph.getEdges(y);
    List<Node> nayx = new ArrayList<Node>();

    for (Edge edge : yEdges) {
      if (!Edges.isUndirectedEdge(edge)) {
        continue;
      }

      Node z = edge.getDistalNode(y);

      if (!graph.isAdjacentTo(z, x)) {
        continue;
      }

      nayx.add(z);
    }

    return nayx;
  }
Esempio n. 12
0
  /** Get all nodes that are connected to Y by an undirected edge and not adjacent to X. */
  private static List<Node> getTNeighbors(Node x, Node y, Graph graph) {
    List<Edge> yEdges = graph.getEdges(y);
    List<Node> tNeighbors = new ArrayList<Node>();

    for (Edge edge : yEdges) {
      if (!Edges.isUndirectedEdge(edge)) {
        continue;
      }

      Node z = edge.getDistalNode(y);

      if (graph.isAdjacentTo(z, x)) {
        continue;
      }

      tNeighbors.add(z);
    }

    return tNeighbors;
  }
Esempio n. 13
0
  private Graph condense(Graph mimStructure, Graph mimbuildStructure) {
    //        System.out.println("Uncondensed: " + mimbuildStructure);

    Map<Node, Node> substitutions = new HashMap<Node, Node>();

    for (Node node : mimbuildStructure.getNodes()) {
      for (Node _node : mimStructure.getNodes()) {
        if (node.getName().startsWith(_node.getName())) {
          substitutions.put(node, _node);
          break;
        }

        substitutions.put(node, node);
      }
    }

    HashSet<Node> nodes = new HashSet<Node>(substitutions.values());
    Graph graph = new EdgeListGraph(new ArrayList<Node>(nodes));

    for (Edge edge : mimbuildStructure.getEdges()) {
      Node node1 = substitutions.get(edge.getNode1());
      Node node2 = substitutions.get(edge.getNode2());

      if (node1 == node2) continue;

      if (graph.isAdjacentTo(node1, node2)) continue;

      graph.addEdge(new Edge(node1, node2, edge.getEndpoint1(), edge.getEndpoint2()));
    }

    //        System.out.println("Condensed: " + graph);

    return graph;
  }
Esempio n. 14
0
  private void correlateExogenousVariables() {
    Graph graph = getWorkbench().getGraph();

    if (graph instanceof Dag) {
      JOptionPane.showMessageDialog(
          JOptionUtils.centeringComp(), "Cannot add bidirected edges to DAG's.");
      return;
    }

    List<Node> nodes = graph.getNodes();

    List<Node> exoNodes = new LinkedList<Node>();

    for (int i = 0; i < nodes.size(); i++) {
      Node node = nodes.get(i);
      if (graph.isExogenous(node)) {
        exoNodes.add(node);
      }
    }

    for (int i = 0; i < exoNodes.size(); i++) {

      loop:
      for (int j = i + 1; j < exoNodes.size(); j++) {
        Node node1 = exoNodes.get(i);
        Node node2 = exoNodes.get(j);
        List<Edge> edges = graph.getEdges(node1, node2);

        for (int k = 0; k < edges.size(); k++) {
          Edge edge = edges.get(k);
          if (Edges.isBidirectedEdge(edge)) {
            continue loop;
          }
        }

        graph.addBidirectedEdge(node1, node2);
      }
    }
  }
Esempio n. 15
0
  private Graph pickDag(Graph graph) {
    SearchGraphUtils.basicPattern(graph, false);
    addRequiredEdges(graph);
    boolean containsUndirected;

    do {
      containsUndirected = false;

      for (Edge edge : graph.getEdges()) {
        if (Edges.isUndirectedEdge(edge)) {
          containsUndirected = true;
          graph.removeEdge(edge);
          Edge _edge = Edges.directedEdge(edge.getNode1(), edge.getNode2());
          graph.addEdge(_edge);
        }
      }

      meekOrient(graph, getKnowledge());
    } while (containsUndirected);

    return graph;
  }
Esempio n. 16
0
  /**
   * Greedy equivalence search: Start from the empty graph, add edges till model is significant.
   * Then start deleting edges till a minimum is achieved.
   *
   * @return the resulting Pattern.
   */
  public Graph search() {

    Graph graph;

    if (initialGraph == null) {
      graph = new EdgeListGraphSingleConnections(getVariables());
    } else {
      graph = new EdgeListGraphSingleConnections(initialGraph);
    }

    fireGraphChange(graph);
    buildIndexing(graph);
    addRequiredEdges(graph);

    topGraphs.clear();

    storeGraph(graph);

    List<Node> nodes = graph.getNodes();

    long start = System.currentTimeMillis();
    score = 0.0;

    // Do forward search.
    fes(graph, nodes);

    // Do backward search.
    bes(graph);

    long endTime = System.currentTimeMillis();
    this.elapsedTime = endTime - start;
    this.logger.log("graph", "\nReturning this graph: " + graph);

    this.logger.log("info", "Elapsed time = " + (elapsedTime) / 1000. + " s");
    this.logger.flush();

    return graph;
  }
Esempio n. 17
0
  // 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);
  }
Esempio n. 18
0
  // Invalid if then nodes or graph changes.
  private void calculateArrowsBackward(Node x, Node y, Graph graph) {
    if (x == y) {
      return;
    }

    if (!graph.isAdjacentTo(x, y)) {
      return;
    }

    if (!knowledgeEmpty()) {
      if (!getKnowledge().noEdgeRequired(x.getName(), y.getName())) {
        return;
      }
    }

    List<Node> naYX = getNaYX(x, y, graph);

    clearArrow(x, y);

    List<Node> _naYX = new ArrayList<Node>(naYX);
    DepthChoiceGenerator gen = new DepthChoiceGenerator(_naYX.size(), _naYX.size());
    int[] choice;

    while ((choice = gen.next()) != null) {
      List<Node> H = GraphUtils.asList(choice, _naYX);

      if (!knowledgeEmpty()) {
        if (!validSetByKnowledge(y, H)) {
          continue;
        }
      }

      double bump = deleteEval(x, y, H, naYX, graph);

      if (bump > 0.0) {
        Arrow arrow = new Arrow(bump, x, y, H, naYX);
        sortedArrows.add(arrow);
        addLookupArrow(x, y, arrow);
      }
    }
  }
Esempio n. 19
0
  private void initializeArrowsBackward(Graph graph) {
    sortedArrows.clear();
    lookupArrows.clear();

    for (Edge edge : graph.getEdges()) {
      Node x = edge.getNode1();
      Node y = edge.getNode2();

      if (!knowledgeEmpty()) {
        if (!getKnowledge().noEdgeRequired(x.getName(), y.getName())) {
          continue;
        }
      }

      if (Edges.isDirectedEdge(edge)) {
        calculateArrowsBackward(x, y, graph);
      } else {
        calculateArrowsBackward(x, y, graph);
        calculateArrowsBackward(y, x, graph);
      }
    }
  }
Esempio n. 20
0
 private void buildIndexing(Graph graph) {
   this.hashIndices = new HashMap<Node, Integer>();
   for (Node node : graph.getNodes()) {
     this.hashIndices.put(node, variables.indexOf(node));
   }
 }
Esempio n. 21
0
  public void rtest3() {
    Node x = new GraphNode("X");
    Node y = new GraphNode("Y");
    Node z = new GraphNode("Z");
    Node w = new GraphNode("W");

    List<Node> nodes = new ArrayList<Node>();
    nodes.add(x);
    nodes.add(y);
    nodes.add(z);
    nodes.add(w);

    Graph g = new EdgeListGraph(nodes);
    g.addDirectedEdge(x, y);
    g.addDirectedEdge(x, z);
    g.addDirectedEdge(y, w);
    g.addDirectedEdge(z, w);

    Graph maxGraph = null;
    double maxPValue = -1.0;
    ICovarianceMatrix maxLatentCov = null;

    Graph mim = DataGraphUtils.randomMim(g, 8, 0, 0, 0, true);
    //        Graph mim = DataGraphUtils.randomSingleFactorModel(5, 5, 8, 0, 0, 0);
    Graph mimStructure = structure(mim);
    SemPm pm = new SemPm(mim);

    System.out.println("\n\nTrue graph:");
    System.out.println(mimStructure);

    SemImInitializationParams params = new SemImInitializationParams();
    params.setCoefRange(0.5, 1.5);

    SemIm im = new SemIm(pm, params);

    int N = 1000;

    DataSet data = im.simulateData(N, false);

    CovarianceMatrix cov = new CovarianceMatrix(data);

    for (int i = 0; i < 1; i++) {

      ICovarianceMatrix _cov = DataUtils.reorderColumns(cov);
      List<List<Node>> partition;

      FindOneFactorClusters fofc = new FindOneFactorClusters(_cov, TestType.TETRAD_WISHART, .001);
      fofc.search();
      partition = fofc.getClusters();
      System.out.println(partition);

      List<String> latentVarList = reidentifyVariables(mim, data, partition, 2);

      Mimbuild2 mimbuild = new Mimbuild2();

      mimbuild.setAlpha(0.001);
      //            mimbuild.setMinimumSize(5);

      // To test knowledge.
      //            Knowledge knowledge = new Knowledge2();
      //            knowledge.setEdgeForbidden("L.Y", "L.W", true);
      //            knowledge.setEdgeRequired("L.Y", "L.Z", true);
      //            mimbuild.setKnowledge(knowledge);

      Graph mimbuildStructure = mimbuild.search(partition, latentVarList, _cov);

      double pValue = mimbuild.getpValue();
      System.out.println(mimbuildStructure);
      System.out.println("P = " + pValue);
      System.out.println("Latent Cov = " + mimbuild.getLatentsCov());

      if (pValue > maxPValue) {
        maxPValue = pValue;
        maxGraph = new EdgeListGraph(mimbuildStructure);
        maxLatentCov = mimbuild.getLatentsCov();
      }
    }

    System.out.println("\n\nTrue graph:");
    System.out.println(mimStructure);
    System.out.println("\nBest graph:");
    System.out.println(maxGraph);
    System.out.println("P = " + maxPValue);
    System.out.println("Latent Cov = " + maxLatentCov);
    System.out.println();
  }
Esempio n. 22
0
  private void addRequiredEdges(Graph graph) {
    if (true) return;
    if (knowledgeEmpty()) return;

    for (Iterator<KnowledgeEdge> it = getKnowledge().requiredEdgesIterator(); it.hasNext(); ) {
      KnowledgeEdge next = it.next();

      Node nodeA = graph.getNode(next.getFrom());
      Node nodeB = graph.getNode(next.getTo());

      if (!graph.isAncestorOf(nodeB, nodeA)) {
        graph.removeEdges(nodeA, nodeB);
        graph.addDirectedEdge(nodeA, nodeB);
        TetradLogger.getInstance()
            .log("insertedEdges", "Adding edge by knowledge: " + graph.getEdge(nodeA, nodeB));
      }
    }
    for (Edge edge : graph.getEdges()) {
      final String A = edge.getNode1().getName();
      final String B = edge.getNode2().getName();

      if (knowledge.isForbidden(A, B)) {
        Node nodeA = edge.getNode1();
        Node nodeB = edge.getNode2();

        if (nodeA != null
            && nodeB != null
            && graph.isAdjacentTo(nodeA, nodeB)
            && !graph.isChildOf(nodeA, nodeB)) {
          if (!graph.isAncestorOf(nodeA, nodeB)) {
            graph.removeEdges(nodeA, nodeB);
            graph.addDirectedEdge(nodeB, nodeA);
            TetradLogger.getInstance()
                .log("insertedEdges", "Adding edge by knowledge: " + graph.getEdge(nodeB, nodeA));
          }
        }
        if (!graph.isChildOf(nodeA, nodeB)
            && getKnowledge().isForbidden(nodeA.getName(), nodeB.getName())) {
          if (!graph.isAncestorOf(nodeA, nodeB)) {
            graph.removeEdges(nodeA, nodeB);
            graph.addDirectedEdge(nodeB, nodeA);
            TetradLogger.getInstance()
                .log("insertedEdges", "Adding edge by knowledge: " + graph.getEdge(nodeB, nodeA));
          }
        }
      } else if (knowledge.isForbidden(B, A)) {
        Node nodeA = edge.getNode2();
        Node nodeB = edge.getNode1();

        if (nodeA != null
            && nodeB != null
            && graph.isAdjacentTo(nodeA, nodeB)
            && !graph.isChildOf(nodeA, nodeB)) {
          if (!graph.isAncestorOf(nodeA, nodeB)) {
            graph.removeEdges(nodeA, nodeB);
            graph.addDirectedEdge(nodeB, nodeA);
            TetradLogger.getInstance()
                .log("insertedEdges", "Adding edge by knowledge: " + graph.getEdge(nodeB, nodeA));
          }
        }
        if (!graph.isChildOf(nodeA, nodeB)
            && getKnowledge().isForbidden(nodeA.getName(), nodeB.getName())) {
          if (!graph.isAncestorOf(nodeA, nodeB)) {
            graph.removeEdges(nodeA, nodeB);
            graph.addDirectedEdge(nodeB, nodeA);
            TetradLogger.getInstance()
                .log("insertedEdges", "Adding edge by knowledge: " + graph.getEdge(nodeB, nodeA));
          }
        }
      }
    }
  }
Esempio n. 23
0
  /** Do an actual deletion (Definition 13 from Chickering, 2002). */
  private void delete(Node x, Node y, List<Node> subset, Graph graph, double bump) {

    Edge trueEdge = null;

    if (trueGraph != null) {
      Node _x = trueGraph.getNode(x.getName());
      Node _y = trueGraph.getNode(y.getName());
      trueEdge = trueGraph.getEdge(_x, _y);
    }

    if (log && verbose) {
      Edge oldEdge = graph.getEdge(x, y);

      String label = trueGraph != null && trueEdge != null ? "*" : "";
      TetradLogger.getInstance()
          .log(
              "deletedEdges",
              (graph.getNumEdges() - 1)
                  + ". DELETE "
                  + oldEdge
                  + " "
                  + subset
                  + " ("
                  + bump
                  + ") "
                  + label);
      out.println(
          (graph.getNumEdges() - 1)
              + ". DELETE "
              + oldEdge
              + " "
              + subset
              + " ("
              + bump
              + ") "
              + label);
    } else {
      int numEdges = graph.getNumEdges() - 1;
      if (numEdges % 50 == 0) out.println(numEdges);
    }

    graph.removeEdge(x, y);

    for (Node h : subset) {
      Edge oldEdge = graph.getEdge(y, h);

      graph.removeEdge(y, h);
      graph.addDirectedEdge(y, h);

      if (log) {
        TetradLogger.getInstance()
            .log("directedEdges", "--- Directing " + oldEdge + " to " + graph.getEdge(y, h));
      }

      if (verbose) {
        out.println("--- Directing " + oldEdge + " to " + graph.getEdge(y, h));
      }

      if (Edges.isUndirectedEdge(graph.getEdge(x, h))) {
        if (!graph.isAdjacentTo(x, h))
          throw new IllegalArgumentException("Not adjacent: " + x + ", " + h);
        oldEdge = graph.getEdge(x, h);

        graph.removeEdge(x, h);
        graph.addDirectedEdge(x, h);

        if (log) {
          TetradLogger.getInstance()
              .log("directedEdges", "--- Directing " + oldEdge + " to " + graph.getEdge(x, h));
        }

        if (verbose) {
          out.println("--- Directing " + oldEdge + " to " + graph.getEdge(x, h));
        }
      }
    }
  }
Esempio n. 24
0
  // serial.
  private void insert(Node x, Node y, List<Node> t, Graph graph, double bump) {
    if (graph.isAdjacentTo(x, y)) {
      return; // The initial graph may already have put this edge in the graph.
      //            throw new IllegalArgumentException(x + " and " + y + " are already adjacent in
      // the graph.");
    }

    Edge trueEdge = null;

    if (trueGraph != null) {
      Node _x = trueGraph.getNode(x.getName());
      Node _y = trueGraph.getNode(y.getName());
      trueEdge = trueGraph.getEdge(_x, _y);
    }

    graph.addDirectedEdge(x, y);

    if (log) {
      String label = trueGraph != null && trueEdge != null ? "*" : "";
      TetradLogger.getInstance()
          .log(
              "insertedEdges",
              graph.getNumEdges()
                  + ". INSERT "
                  + graph.getEdge(x, y)
                  + " "
                  + t
                  + " "
                  + bump
                  + " "
                  + label);
    } else {
      int numEdges = graph.getNumEdges() - 1;
      if (verbose) {
        if (numEdges % 50 == 0) out.println(numEdges);
      }
    }

    if (verbose) {
      String label = trueGraph != null && trueEdge != null ? "*" : "";
      out.println(
          graph.getNumEdges()
              + ". INSERT "
              + graph.getEdge(x, y)
              + " "
              + t
              + " "
              + bump
              + " "
              + label);
    } else {
      int numEdges = graph.getNumEdges() - 1;
      if (verbose) {
        if (numEdges % 50 == 0) out.println(numEdges);
      }
    }

    for (Node _t : t) {
      Edge oldEdge = graph.getEdge(_t, y);

      if (oldEdge == null) throw new IllegalArgumentException("Not adjacent: " + _t + ", " + y);

      graph.removeEdge(_t, y);
      graph.addDirectedEdge(_t, y);

      if (log && verbose) {
        TetradLogger.getInstance()
            .log("directedEdges", "--- Directing " + oldEdge + " to " + graph.getEdge(_t, y));
        out.println("--- Directing " + oldEdge + " to " + graph.getEdge(_t, y));
      }
    }
  }