@Override
double aggregate(final List<Integer> values) {
// avoid division by zero
if (values.isEmpty()) {
return 0.0;
}
return SUM.aggregate(values) / AMOUNT.aggregate(values);
}
public double getStatistics(Attribute attribute, String name, String parameter) {
if (AVERAGE.equals(name)) {
return this.sum / this.valueCounter;
} else if (VARIANCE.equals(name)) {
if (valueCounter <= 1) {
return 0;
}
double variance = (squaredSum - (sum * sum) / valueCounter) / (valueCounter - 1);
if (variance < 0) // this is due to rounding errors above
return 0;
return variance;
} else if (SUM.equals(name)) {
return this.sum;
} else {
LogService.getGlobal()
.log("Cannot calculate statistics, unknown type: " + name, LogService.WARNING);
return Double.NaN;
}
}
public boolean handleStatistics(String name) {
return AVERAGE.equals(name) || VARIANCE.equals(name) || SUM.equals(name);
}
