Instance c = new DenseInstance(2);
c.setValue(stringAttr, "nothing here");
c.setValue(anotherAttr, 0);
instances.add(c);
inputFormat.addAll(instances);
filter.setInputFormat(inputFormat);
Instances output = filter.getOutputFormat();
for (int i = 0; i < instances.size(); i++) {
Instance original = inputFormat.get(i);