abstractdataindexer.java

最大熵分类器

///////////////////////////////////////////////////////////////////////////////
//Copyright (C) 2003 Thomas Morton
//
//This library is free 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 2.1 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 program; if not, write to the Free Software
//Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.
//////////////////////////////////////////////////////////////////////////////
package opennlp.maxent;

import gnu.trove.TObjectIntHashMap;
import gnu.trove.TObjectIntProcedure;

import java.util.Collections;
import java.util.List;
import java.util.Set;

/**
 * Abstract class for collecting event and context counts used in training. 
 *
 */
public abstract class AbstractDataIndexer implements DataIndexer {

  /** The integer contexts associated with each unique event. */ 
  protected int[][] contexts;
  /** The integer outcome associated with each unique event. */ 
  protected int[] outcomeList;
  /** The number of times an event occured in the training data. */
  protected int[] numTimesEventsSeen;
  /** The predicate/context names. */
  protected String[] predLabels;
  /** The names of the outcomes. */
  protected String[] outcomeLabels;
  /** The number of times each predicate occured. */
  protected int[] predCounts;

  public int[][] getContexts() {
    return contexts;
  }

  public int[] getNumTimesEventsSeen() {
    return numTimesEventsSeen;
  }

  public int[] getOutcomeList() {
    return outcomeList;
  }

  public String[] getPredLabels() {
    return predLabels;
  }

  public String[] getOutcomeLabels() {
    return outcomeLabels;
  }
  
  

  public int[] getPredCounts() {
    return predCounts;
  }

  /**
       * Sorts and uniques the array of comparable events and return the number of unique events.
       * This method will alter the eventsToCompare array -- it does an in place
       * sort, followed by an in place edit to remove duplicates.
       *
       * @param eventsToCompare a <code>ComparableEvent[]</code> value
       * @return The number of unique events in the specified list.
       * @since maxent 1.2.6
       */
  protected int sortAndMerge(List eventsToCompare) {
    Collections.sort(eventsToCompare);
    int numEvents = eventsToCompare.size();
    int numUniqueEvents = 1; // assertion: eventsToCompare.length >= 1

    if (numEvents <= 1) {
      return numUniqueEvents; // nothing to do; edge case (see assertion)
    }

    ComparableEvent ce = (ComparableEvent) eventsToCompare.get(0);
    for (int i = 1; i < numEvents; i++) {
      ComparableEvent ce2 = (ComparableEvent) eventsToCompare.get(i);

      if (ce.compareTo(ce2) == 0) {
        ce.seen++; // increment the seen count
        eventsToCompare.set(i, null); // kill the duplicate
      }
      else {
        ce = ce2; // a new champion emerges...
        numUniqueEvents++; // increment the # of unique events
      }
    }

    System.out.println("done. Reduced " + numEvents + " events to " + numUniqueEvents + ".");

    contexts = new int[numUniqueEvents][];
    outcomeList = new int[numUniqueEvents];
    numTimesEventsSeen = new int[numUniqueEvents];

    for (int i = 0, j = 0; i < numEvents; i++) {
      ComparableEvent evt = (ComparableEvent) eventsToCompare.get(i);
      if (null == evt) {
        continue; // this was a dupe, skip over it.
      }
      numTimesEventsSeen[j] = evt.seen;
      outcomeList[j] = evt.outcome;
      contexts[j] = evt.predIndexes;
      ++j;
    }
    return numUniqueEvents;
  }
  
  /**
   * Updates the set of predicated and counter with the specified event contexts and cutoff. 
   * @param ec The contexts/features which occur in a event.
   * @param predicateSet The set of predicates which will be used for model building.
   * @param counter The predicate counters.
   * @param cutoff The cutoff which determines whether a predicate is included.
   */
   protected static void update(String[] ec, Set predicateSet, TObjectIntHashMap counter, int cutoff) {
    for (int j=0; j<ec.length; j++) {
      if (!counter.increment(ec[j])) {
        counter.put(ec[j], 1);
      }
      if (!predicateSet.contains(ec[j]) && counter.get(ec[j]) >= cutoff) {
        predicateSet.add(ec[j]);
      }
    }
  }

  /**
   * Utility method for creating a String[] array from a map whose
   * keys are labels (Strings) to be stored in the array and whose
   * values are the indices (Integers) at which the corresponding
   * labels should be inserted.
   *
   * @param labelToIndexMap a <code>TObjectIntHashMap</code> value
   * @return a <code>String[]</code> value
   * @since maxent 1.2.6
   */
  protected static String[] toIndexedStringArray(TObjectIntHashMap labelToIndexMap) {
    final String[] array = new String[labelToIndexMap.size()];
    labelToIndexMap.forEachEntry(new TObjectIntProcedure() {
      public boolean execute(Object str, int index) {
        array[index] = (String)str;
        return true;
      }
    });
    return array;
  }

  public float[][] getValues() {
    return null;
  }
  
  
}