def _valley_ridge_names(scale, mode, smth_factor):
    """Return names for the arrays in output of the valley_ridge function"""

    add = f"_SMTHFACT{smth_factor:.3g}" if smth_factor else ""
    name_norm = f"{mode}_NORM_{scale}M{add}"
    name_dir = f"{mode}_DIR_{scale}M{add}"

    return [name_norm, name_dir]