util.java

Boosting算法软件包

package jboost.util;

import java.util.Arrays;

/** A class holding miscellaneous utility functions */
public class Util{
    /** A generic intersect function that
     *  @param mask An examples mask
     *  @param examples The list of examples to intersect with
     *  @param intersection The examples mask with the intersection of the first 2 arguments,
     *         must be the same size as mask.
     *  @return The number of true elements in the intersection mask.		*/
    public static int intersect(boolean[] mask,int[] examples,boolean[] intersection) {
	if(intersection.length!=mask.length) 	
	    throw new RuntimeException("Argument and return value have different length.");
	Arrays.fill(intersection,false);
	int count=0;
        for(int i=0;i<examples.length;i++)
            if(mask[examples[i]]) {
            	intersection[examples[i]]=true;
		    count++;
	}
        return(count);
    }

    /** Determines whether an integer is even.
     */
    public static boolean even(int i) {return (i/2*2 == i);}

    /** Determines whether an integer is odd.
     */
    public static boolean odd(int i) {return (i/2*2 != i);}
}