*/
public void exportBagOfWords(String arffRelation,
String instanceClassQuery, String instanceNumericWordQuery,
String instanceNominalWordQuery, BufferedWriter writer,
BagOfWordsDecorator bDecorator) throws IOException {
BagOfWordsData bagOfWordsData = new BagOfWordsData();
// load instance classes
getInstances(instanceClassQuery, bagOfWordsData);
loadData(bagOfWordsData, instanceNumericWordQuery,
instanceNominalWordQuery, bDecorator);
// add instance for each document