for (int index = 0; index < values.length; index++) {
Data subset = data.subset(Condition.equals(best.getAttr(), values[index]));
children[index] = build(rng, subset);
}
childNode = new CategoricalNode(best.getAttr(), values, children);
if (!alreadySelected) {
selected[best.getAttr()] = false;
}
}