instanceInfo = new Instances(instanceInfo, 0); // copy before modifying
Attribute oldAtt = instanceInfo.attribute(m_AttIndex.getIndex());
int [] selection = m_Values.getSelection();
FastVector newVals = new FastVector();
for (int i = 0; i < selection.length; i++) {
newVals.addElement(oldAtt.value(selection[i]));
}
instanceInfo.deleteAttributeAt(m_AttIndex.getIndex());
instanceInfo.insertAttributeAt(new Attribute(oldAtt.name(), newVals),
m_AttIndex.getIndex());
m_NominalMapping = new int [oldAtt.numValues()];