/*

  * Created on 12.08.2006

  *

  */

 package net.sourceforge.combean.mathprog.linalg.statics;

 import java.util.Set;

 import java.util.TreeSet;

 import net.sourceforge.combean.interfaces.mathprog.linalg.SparseVec;

 import net.sourceforge.combean.interfaces.mathprog.linalg.VectorIterator;

 /**

  * A collection of utility function to calculate with sparse vectors

  * 

  * @author schickin

  *

  */

 public class SparseVectorUtil {

     /**

      * Calculate the sum of the components of the vector

      * 

      * @param vec a sparse vector

      * @return the sum of the components of vec

      */

     public static final <Label> double sum(SparseVec<Label> vec) {

         double result = 0.0;

         VectorIterator<Label> itVec = vec.iterator();

         while (itVec.hasNext()) {

             result += itVec.next().doubleValue();

         }

         return result;

     }

     public static final <Label> Set<Label> collectLabels(SparseVec<Label> vec) {

         Set<Label> labels = new TreeSet<Label>();

         VectorIterator<Label> itVec = vec.iterator();

         while (itVec.hasNext()) {

             labels.add(itVec.next().label());

         }

         return labels;

     }

 }