FastVector newClassVals = new FastVector(numNonEmptyClasses);
int[] oldIndexToNewIndex = new int[newTrain.numClasses()];
for (int i = 0; i < newTrain.numClasses(); i++) {
if (notEmptyClass[i]) {
oldIndexToNewIndex[i] = newClassVals.size();
newClassVals.addElement(newTrain.classAttribute().value(i));
}
}
// Compute new header information
Attribute newClass = new Attribute(newTrain.classAttribute().name(),