text:                 fprintf(stderr, "%4d: features dim: %lu x %lu - [%.8g, %.8g, ...] label dim: %d x %d - [%d, %d, ...]\n", i, features.GetNumRows(), features.GetNumCols(), features(0, 0), features(0, 1), labels.GetNumRows(), labels.GetNumCols(), (int) labels(0, 0), (int) labels(0, 1));
  