splitter.java

Boosting算法软件包

package jboost.learner;

import java.io.Serializable;

import jboost.examples.AttributeDescription;
import jboost.examples.ExampleSet;
import jboost.examples.Instance;

/**
 * A splitter recieves an example and returns -1 for "I don't know" or a non-negative 
 * integer for a (non-abstaining) classification
 */
public abstract class Splitter implements Cloneable,Serializable {
  
  /** the type of this splitter */
  protected SplitterType m_type;
  
  /**
   * Return the type of this splitter. 
   * Uses the value of the SplitterType
   * @return the SplitterType
   */
  public SplitterType getType() {
    return m_type;
  }
  
/**
 * Return the partition in which an instance belongs. 
 * returning -1 signifies "partition unknown" 
 */
    public abstract int eval(Instance instance) throws IncompAttException;

/**
 * Compute the partition for a list of instances. 
 * @param exampleSet The set that contains the examples to be partitioned.
 * @param indices An array of the relevant indices in exampleSet
 * @return A new array of arrays of integers
 *         where each array of integers is a list of the examples in
 *         that partition 
 */
    public int[][] partition(ExampleSet exampleSet, int[] indices) 
			throws IncompAttException, PartitionException {
	if(degree==-1) throw(new PartitionException("This splitter had degree: "+degree));
	int[][] part=new int[degree][];
	int[] count=new int[degree];
	int length = indices.length;
	int i=0;
	for(i=0;i<degree;i++) {
	    part[i]=new int[length];
	}
	int j=0;
	int p=0;
	for(i=0; i<length; i++) {
	    j = indices[i];
	    p = eval(exampleSet.getExample(j).getInstance());
	    if(p<0) continue;
	    part[p][count[p]]=j;
	    count[p]++;
	}
	int[][] retval=new int[degree][];
	for(i=0;i<degree;i++) {
	    retval[i]=new int[count[i]];
	    System.arraycopy(part[i],0,retval[i],0,count[i]);
	}
	return(retval);
    }

    /** Create a copy of this splitter */
    public abstract Object clone();

    /** Returns a string describing this splitter */
    public abstract String toString();

  /** Produces a java implementation of this splitter.                          */
   public abstract String toJava(String fname);

  /** Produces a java implementation of this splitter.                          */
   public abstract String toC(String fname);

  /** Produces a summary if possible, should be useful for producing efficient
   *  code.									*/
   public Summary getSummary() {
	return(null);
   }

  /** Determines whether two splitters calculate the same split.		*/
   public abstract boolean equals(Splitter sp);

//--------------------------- Protected Members ---------------------------------//

    /** The attribute index this splitter refers to */
    protected int index;
    protected AttributeDescription desc;
    public int getIndex() {return(index);}

    /** Holds the degree of the split */
    protected int degree=-1;
    protected int getDegree() { return(degree);}
}

class PartitionException extends Exception {
	PartitionException(String m) {
		super(m);
	}
}