code: public double averageFalseAlarmRate() {
          double ret = 0.0;
          for (int i = 0; i < numLabels(); i++) {
              ret += falseAlarmRate(i);
          }
  
          ret /= (double) numLabels();
          return ret;
      }
docs: Average False Alarm Rate (FAR) (see {@link #falseAlarmRate(int)}) for all labels.
  
  @return The FAR for all labels.