/* Copyright 2003, Carnegie Mellon, All Rights Reserved */
package edu.cmu.minorthird.classify;
/** Marker interface for objects which support the
* 'getSubpopulationId' method.
*
* @author William Cohen
*/
public interface HasSubpopulationId
{
/** Get the subpopulation from which this instance was drawn.
* A null id is considered to be a unique subpopulation---different
* from every other subpopulation, including other nulls.
* A subpopulation is a subset of the training data which is
* expected to contain additional regularities - for instance,
* pages from the same site, or spans from the same document.
* Testing routines may use subpopulation's to more correctly
* spit datasets into train/test subsets.
*/
public String getSubpopulationId();
}