scoredcomparator.java

Standord Classifier实现了一个基于Java的最大熵分类器。用于模式识别

package edu.stanford.nlp.util;

import java.util.*;

/**
 *  ScoredComparator:  Interface for comparing scored things.
 *
 *  @author Dan Klein
 *  @version 12/4/00
 */
final public class ScoredComparator implements Comparator {

  public static final boolean ASCENDING = true;
  public static final boolean DESCENDING = false;

  public static final ScoredComparator ASCENDING_COMPARATOR = 
      new ScoredComparator(ASCENDING);

  public static final ScoredComparator DESCENDING_COMPARATOR = 
      new ScoredComparator(DESCENDING);

  private final boolean ascending;

  public ScoredComparator() {ascending = ASCENDING;}

  public ScoredComparator(boolean ascending) {
    this.ascending = ascending;
  }

  public int compare(Object o1, Object o2) {
    if (o1 == o2)
      return 0;
    /*if (! (o1 instanceof Scored) ||
	! (o2 instanceof Scored))
	throw new ClassCastException();*/
    double d1 = ((Scored)o1).score();
    double d2 = ((Scored)o2).score();
    if(ascending) {
      if (d1 < d2)
	return -1;
      if (d1 > d2)
	return 1;
    } else {
      if (d1 < d2)
	return 1;
      if (d1 > d2)
	return -1;
    }
    return 0;
  }

  public boolean equals(Object o) {
    if (o==this)
      return true;
    if (o instanceof ScoredComparator) {
      ScoredComparator sc = (ScoredComparator) o;
      if (ascending == sc.ascending)
	return true;
    }
    return false;
  }

}