def _get_stat_float(label_result_dict, stat):
    if stat in label_result_dict and label_result_dict[stat] is not None:
        return label_result_dict[stat]
    else:
        return float('nan')
Little helper for getting output for precision, recall, and f-score
dataset/ETHPy150Open EducationalTestingService/skll/skll/experiments.py/_get_stat_float