setsplitter.java

Boosting算法软件包

package jboost.learner;

import java.util.Arrays;

import jboost.examples.Attribute;
import jboost.examples.AttributeDescription;
import jboost.examples.Instance;
import jboost.examples.SetAttribute;

/*
 * Splits examples according to whether the intersection of a
 * <i>SetAttribute</> and a fixed list of tokens is non-empty.
 */
class SetSplitter extends Splitter {
    private int token;	// The index of the token on which the split is based
    private boolean abstain; // abstaining flag when token does not appear 

    public int getToken() {
	return token;
    }

    public boolean isAbstaining() {
	return abstain;
    }

    public SetSplitter(int i, int t, boolean a,AttributeDescription ad) {
	index = i;
	token = t;
	abstain = a;
	desc=ad;
	m_type= SplitterType.SET_SPLITTER;
    }

	/*
	 *	Return the partition to which the token belongs.
	 *
	 *	When NOT abstaining:
	 *  --------------------
	 *		-1 - signifies "partition unknown" (e.g. attribute not defined)
	 *		 0 - siginifies that the token appears in the attribute
	 *		+1 - siginifies that the token does not appear in the attribute
	 *
	 *	When abstaining:
	 *  ----------------
	 *		-1 - signifies "partition unknown" (e.g. attribute not defined)
	 *           OR token does not appear
	 *		 0 - siginifies that the token appears in the attribute
	 */
// CHANGED - name from partition to eval.
	public int eval(Instance instance) throws IncompAttException {

		Attribute t = instance.getAttribute(index);

		if (t == null) {
			return(-1);
		}

		SetAttribute a = (SetAttribute) t;	// try downcasting 

		return (Arrays.binarySearch(a.getList(), token) >= 0 ?
			0 : (abstain ? -1 : 1));
	}


	/* return the number of splits of a setSplitter */
	public int getDegree() {
		if (abstain)
			return 1;
		else
			return 2;
	}

// CHANGED - name from copy() to clone()
	public Object clone() {
		SetSplitter ss = new SetSplitter(index, token, abstain,desc);
		return ss;
	}


	/** Returns a string describing this splitter **/
	public String toString() {
		String s=null;
		try{
			s = new String(
				"Attribute:" + desc.getAttributeName() 
				+ " Token:" +desc.getAttributeValue(token) 
				+ " Abstain: " + abstain);
		} catch(IncompAttException e){ 
		    s= new String
			("Incompatible attribute description:"+ desc.getClass());
		}
		return s;
	}

// ADDED

       /** Returns a string containing Java code.				*/
	public String toJava(String fname) {
		return(null);
	}

       /** Returns a string containing Java code.				*/
	public String toC(String fname) {
		return(null);
	}


    public boolean equals(Splitter sp) {
        SetSplitter isp;
        try{isp=(SetSplitter)sp;}
        catch(ClassCastException e) {
                return(false);
        }
        if(index==isp.index && token==isp.token && abstain==isp.abstain) return(true);
        else return(false);
    }

   /** Get a summary.                                                   */
    public Summary getSummary() {
        Summary retval=new Summary();
        retval.index=index;
        retval.type = (abstain
		       ? Summary.CONTAINS_ABSTAIN
		       : Summary.CONTAINS_NOABSTAIN);
	retval.val = desc.getAttributeValue(token);
        return(retval);
    }

// END_ADDED
}