code: public static double fBeta(double beta, long tp, long fp, long fn) {
          double prec = tp / ((double) tp + fp);
          double recall = tp / ((double) tp + fn);
          return fBeta(beta, prec, recall);
      }
docs: Calculate the F beta value from counts
  
  @param beta Beta of value to use
  @param tp   True positive count
  @param fp   False positive count
  @param fn   False negative count
  @return F beta