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.util.TetradSerializable;
  
  /**
   * Stores a 2D array of data. Different implementations may store data in
   * different ways, allowing for space or time efficiency.
   *
   * @author Joseph Ramsey
   */
  public interface DataBox extends TetradSerializable {
      long serialVersionUID = 23L;
  
      /**
       * @return the (fixed) number of rows of the dataset.
       */
      int numRows();
  
      /**
       * @return the (fixed) number of columns of the dataset.
       */
      int numCols();
  
      /**
       * Sets the value at the given row and column to the given Number. This
       * number may be interpreted differently depending on how values are
       * stored. A value of null is interpreted as a missing value.
       *
       * @throws IllegalArgumentException if the given value cannot be stored
       *                                  (because it's out of range or cannot be converted or whatever).
       */
      void set(int row, int col, Number value) throws IllegalArgumentException;
  
      /**
       * @return the value at the given row and column as a Number. If the
       * value is missing, null is uniformly returned.
       */
      Number get(int row, int col);
  
      /**
       * @return a copy of this data box.
       */
      DataBox copy();
  
      /**
       * @return this data box, restricted to the given rows and columns.
       */
      DataBox viewSelection(int[] rows, int[] cols);
  
      DataBox like();
  }
  
  
  
  
  