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.data;
  
  import edu.cmu.tetrad.graph.Node;
  import edu.cmu.tetrad.util.TetradMatrix;
  
  import java.io.IOException;
  import java.io.ObjectInputStream;
  import java.util.ArrayList;
  import java.util.LinkedList;
  import java.util.List;
  
  /**
   * Stores time series data as a list of continuous columns.
   *
   * @author Joseph Ramsey
   */
  public final class TimeSeriesData implements DataModel {
      static final long serialVersionUID = 23L;
  
      /**
       * @serial
       */
      private TetradMatrix data2;
  
      /**
       * @serial
       */
      private String name;
  
      /**
       * @serial
       */
      private List<String> varNames;
  
      /**
       * @serial
       */
      private IKnowledge knowledge = new Knowledge2();
  
      //==============================CONSTRUCTOR===========================//
  
      /**
       * Constructs a new time series data contains for the given row-major data
       * array and the given list of variables. Each row of the data, data[i],
       * contains a measured for each variable (in order) for a particular time.
       * The series of times is in increasing order.
       */
      public TimeSeriesData(TetradMatrix matrix, List<String> varNames) {
          if (matrix == null) {
              throw new NullPointerException("Data must not be null.");
          }
  
          if (varNames == null) {
              throw new NullPointerException("Variables must not be null.");
          }
          for (int i = 0; i < varNames.size(); i++) {
              if (varNames.get(i) == null) {
                  throw new NullPointerException(
                          "Variable at index " + i + "is null.");
              }
          }
          this.data2 = matrix;
          if (varNames.size() != matrix.columns()) {
              throw new IllegalArgumentException(
                      "Number of columns in the data " +
                              "must match the number of variables.");
          }
          this.varNames = varNames;
          this.name = "Time Series Data";
      }
  
      /**
       * Generates a simple exemplar of this class to test serialization.
       */
      public static TimeSeriesData serializableInstance() {
          List<String> varNames = new ArrayList<>();
          varNames.add("X");
          varNames.add("Y");
          return new TimeSeriesData(new TetradMatrix(2, 2), varNames);
      }
  
      //=================================PUBLIC METHODS======================//
  
      public final String getName() {
          return this.name;
      }
  
      public final void setName(String name) {
          if (name == null) {
              throw new NullPointerException("Name must not be null.");
          }
          this.name = name;
      }
  
      @Override
      public boolean isContinuous() {
          return true;
      }
  
      @Override
      public boolean isDiscrete() {
          return false;
      }
  
      @Override
      public boolean isMixed() {
          return false;
      }
  
      @Override
      public Node getVariable(String name) {
          return null;
      }
  
      @Override
      public DataModel copy() {
          return null;
      }
  
      public final List<Node> getVariables() {
          List<String> varNames = getVariableNames();
          List<Node> vars = new LinkedList<>();
  
          for (Object varName : varNames) {
              vars.add(new ContinuousVariable((String) varName));
          }
  
          return vars;
      }
  
      public final IKnowledge getKnowledge() {
          System.out.println();
  
          return this.knowledge.copy();
      }
  
      public final void setKnowledge(IKnowledge knowledge) {
          if (knowledge == null) {
              throw new NullPointerException();
          }
  
          this.knowledge = knowledge.copy();
      }
  
      /**
       * @return (a copy of) the List of Variables for the data set, in the order
       * of their columns.
       */
      public final List<String> getVariableNames() {
          return this.varNames;
      }
  
      public final TetradMatrix getData() {
          return data2.copy();
      }
  
      public final int getNumTimePoints() {
          return getData().rows();
      }
  
      public final int getNumVars() {
          return getVariableNames().size();
      }
  
      public final double getDatum(int row, int col) {
          return this.data2.get(row, col);
      }
  
      /**
       * Adds semantic checks to the default deserialization method. This method
       * must have the standard signature for a readObject method, and the body of
       * the method must begin with "s.defaultReadObject();". Other than that, any
       * semantic checks can be specified and do not need to stay the same from
       * version to version. A readObject method of this form may be added to any
       * class, even if Tetrad sessions were previously saved out using a version
       * of the class that didn't include it. (That's what the
       * "s.defaultReadObject();" is for. See J. Bloch, Effective Java, for help.
       *
       * @throws java.io.IOException
       * @throws ClassNotFoundException
       */
      private void readObject(ObjectInputStream s)
              throws IOException, ClassNotFoundException {
          s.defaultReadObject();
  
          if (name == null) {
              throw new NullPointerException();
          }
  
          if (varNames == null) {
              throw new NullPointerException();
          }
  
          if (knowledge == null) {
              throw new NullPointerException();
          }
      }
  }
  
  
  
  
  