private double getGiniIndex(ClassificationCounter cc) {
double sum = 0.0d;
for (Map.Entry<Serializable, Double> e : cc.getCounts().entrySet()) {
double error = (cc.getTotal() > 0) ? e.getValue() / cc.getTotal() : 0;
sum += error * error;
}
return 1.0d - sum;
}
