def METHOD_NAME(self, data_root_path, subdir):
    _index = 1
    _indes_str = "%04d" % _index
    fpath = os.path.join(data_root_path, f"{subdir}_{_indes_str}")
    while os.path.exists(fpath):
        _index += 1
        _indes_str = "%04d" % _index
        fpath = os.path.join(data_root_path, f"{subdir}_{_indes_str}")
    return fpath