numberer.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.*;
import java.io.Serializable;

/** Gives a unique integer serial numbers to a family of objects, identified
 *  by a name space.
 *  @author Dan Klein
 */
public class Numberer implements Serializable {

  private static Map numbererMap = new HashMap();

  public static Map getNumberers() { return numbererMap; }

  public static void setNumberers(Map numbs) { numbererMap = numbs; }


  public static Numberer getGlobalNumberer(String type) {
    Numberer n = (Numberer) numbererMap.get(type);
    if (n==null) {
      n = new Numberer();
      numbererMap.put(type, n);
    }
    return n;
  }


  public static int number(String type, Object o) {
    return getGlobalNumberer(type).number(o);
  }


  public static Object object(String type, int n) {
    return getGlobalNumberer(type).object(n);
  }


  public static int translate(String sourceType, String targetType, int n) {
    return getGlobalNumberer(targetType).number(getGlobalNumberer(sourceType).object(n));
  }


  private int total;
  private Map intToObject;
  private Map objectToInt;
  private MutableInteger tempInt;
  private boolean locked = false;


  public int total() {
    return total;
  }


  public void lock() {
    locked = true;
  }


  public boolean hasSeen(Object o) {
    return objectToInt.keySet().contains(o);
  }


  public int number(Object o) {
    MutableInteger i = (MutableInteger)objectToInt.get(o);
    if (i == null) {
      if (locked) {
	throw new NoSuchElementException();
      }
      i = new MutableInteger(total);
      total++;
      objectToInt.put(o,i);
      intToObject.put(i,o);
    }
    return i.intValue();
  }


  public Object object(int n) {
    tempInt.set(n);
    return intToObject.get(tempInt);
  }


  public String toString() {
    StringBuffer sb = new StringBuffer();
    sb.append("[");
    for (int i=0; i<total; i++) {
      sb.append(i);
      sb.append("->");
      sb.append(object(i));
      if (i < total-1)
	sb.append(", ");
    }
    sb.append("]");
    return sb.toString();
  }


  public Numberer() {
    total = 0;
    tempInt = new MutableInteger();
    intToObject = new HashMap();
    objectToInt = new HashMap();
  }


  private static final long serialVersionUID = 1L;

}