code: public String getAccuracyDescription(int numDigits) {
      NumberFormat nf = NumberFormat.getNumberInstance();
      nf.setMaximumFractionDigits(numDigits);
      Triple<Double, Integer, Integer> accu = getAccuracyInfo();
      return nf.format(accu.first()) + "  (" + accu.second() + "/" + (accu.second() + accu.third()) + ")";
    }
docs: Returns a String summarizing overall accuracy that will print nicely.