/**
 *   
 *   AgentAcademy - an open source Data Mining framework for
 *   training intelligent agents
 *
 *   Copyright (C)   2001-2003 AA Consortium.
 *
 *   This library is open source software; you can redistribute it 
 *   and/or modify it under the terms of the GNU Lesser General 
 *   Public License as published by the Free Software Foundation;   
 *   either version 2.0 of the License, or (at your option) any later 
 *   version.
 *
 *   This library 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 Lesser General Public
 *   License along with this library; if not, write to the Free 
 *   Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, 
 *   MA  02111-1307 USA
 * 
 */

package org.agentacademy.modules.dataminer.attributeSelection;

import org.agentacademy.modules.dataminer.core.Instance;
import org.agentacademy.modules.dataminer.core.Instances;

public interface AttributeTransformer {
    // ===============
    // Public methods.
    // ===============

  /**
   * Returns just the header for the transformed data (ie. an empty
   * set of instances. This is so that AttributeSelection can
   * determine the structure of the transformed data without actually
   * having to get all the transformed data through getTransformedData().
   * @return the header of the transformed data.
   * @exception Exception if the header of the transformed data can't
   * be determined.
   */
  Instances transformedHeader() throws Exception;

  /**
   * Returns the transformed data
   * @return A set of instances representing the transformed data
   * @exception Exception if the attribute could not be evaluated
   */
  Instances transformedData() throws Exception;

  /**
   * Transforms an instance in the format of the original data to the
   * transformed space
   * @return a transformed instance
   * @exception Exception if the instance could not be transformed
   */
  Instance convertInstance(Instance instance) throws Exception;
}