public static double[] rank(ExampleSet eSet,Attribute att,Attribute mappingAtt){
  return rank(eSet,att,mappingAtt,0.0);
}

public static double [ ] rank ( ExampleSet eSet , Attribute att , Attribute mappingAtt ) { return rank ( eSet , att , mappingAtt , 0.0 ) ; }
calculates ranks for an attribute . ranks are returned as double precision values , with 1 as the rank of the smallest value . tied values receive identical ranks . missing values receive rank nan .
