docs: public double accuracy() {
          if (getNumRowCounter() == 0) {
              return 0.0; //No records
          }
          //Accuracy: sum the counts on the diagonal of the confusion matrix, divide by total
          int nClasses = confusion().getClasses().size();
          int countCorrect = 0;
          for (int i = 0; i < nClasses; i++) {
              countCorrect += confusion().getCount(i, i);
          }
  
          return countCorrect / (double) getNumRowCounter();
      }