code: ///////////////////////////////////////////////////////////////////////////////
  // For information as to what this class does, see the Javadoc, below.       //
  // Copyright (C) 1998, 1999, 2000, 2001, 2002, 2003, 2004, 2005, 2006,       //
  // 2007, 2008, 2009, 2010, 2014, 2015 by Peter Spirtes, Richard Scheines, Joseph   //
  // Ramsey, and Clark Glymour.                                                //
  //                                                                           //
  // This program is free software; you can redistribute it and/or modify      //
  // it under the terms of the GNU General Public License as published by      //
  // the Free Software Foundation; either version 2 of the License, or         //
  // (at your option) any later version.                                       //
  //                                                                           //
  // This program is distributed in the hope that it will be useful,           //
  // but WITHOUT ANY WARRANTY; without even the implied warranty of            //
  // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the             //
  // GNU General Public License for more details.                              //
  //                                                                           //
  // You should have received a copy of the GNU General Public License         //
  // along with this program; if not, write to the Free Software               //
  // Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA //
  ///////////////////////////////////////////////////////////////////////////////
  
  package edu.cmu.tetrad.gene.tetrad.gene.history;
  
  import java.util.ArrayList;
  import java.util.List;
  
  /**
   * Initializes a graph by adding the previous time step only of each variable.
   *
   * @author Joseph Ramsey jdramsey@andrew.cmu.edu
   */
  public class PreviousStepOnly implements GraphInitializer {
      public PreviousStepOnly() {
      }
  
      /**
       * Randomizes the graph.
       */
      public void initialize(LagGraph lagGraph) {
  
          lagGraph.clearEdges();
  
          List<String> factors = new ArrayList<>(lagGraph.getFactors());
  
          // Add edges one time step back.
          for (String factor1 : factors) {
              LaggedFactor laggedFactor = new LaggedFactor(factor1, 1);
              lagGraph.addEdge(factor1, laggedFactor);
          }
      }
  }
  
  
  
  
  
  