Package edu.cmu.tetrad.search.utils

Class DagIterator

java.lang.Object
edu.cmu.tetrad.search.utils.DagIterator
public class DagIterator extends Object
Given a graph, lists all DAGs that result from directing the undirected edges in that graph every possible way. Uses a Meek-algorithm-type method.
Version:
$Id: $Id
Author:
josephramsey

  • Constructor Summary

    Constructors
    Constructor
    Description
    DagIterator(Graph CPDAG)
    The given CPDAG must be a CPDAG.

  • Method Summary

    Modifier and Type
    Method
    Description
    boolean
    hasNext()
    Returns true just in case there is still a DAG remaining in the enumeration of DAGs for this pattern.
    Graph
    next()
    Successive calls to this method return successive DAGs in the CPDAG, in a more or less natural enumeration of them in which an arbitrary undirected edge is picked, oriented one way, Meek rules applied, then a remaining unoriented edge is picked, oriented one way, and so on, until a DAG is obtained, and then by backtracking the other orientation of each chosen edge is tried.

    Methods inherited from class java.lang.Object

    equals, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

  • Constructor Details

    • DagIterator

      public DagIterator(Graph CPDAG)
      The given CPDAG must be a CPDAG. If it does not consist entirely of directed and undirected edges and if it is not acyclic, it is rejected.
      Parameters:
      CPDAG - a Graph object
      Throws:
      IllegalArgumentException - if the CPDAG is not a CPDAG.

  • Method Details

    • next

      public Graph next()
      Successive calls to this method return successive DAGs in the CPDAG, in a more or less natural enumeration of them in which an arbitrary undirected edge is picked, oriented one way, Meek rules applied, then a remaining unoriented edge is picked, oriented one way, and so on, until a DAG is obtained, and then by backtracking the other orientation of each chosen edge is tried. Nonrecursive, obviously.
      Returns:
      a Graph instead of a DAG because sometimes, due to faulty patterns, a cyclic graph is produced, and the end-user may need to decide what to do with it. The simplest thing is to construct a DAG (Dag(graph)) and catch an exception.

    • hasNext

      public boolean hasNext()
      Returns true just in case there is still a DAG remaining in the enumeration of DAGs for this pattern.
      Returns:
      true just in case there is still a DAG remaining in the enumeration of DAGs for this pattern.