if scaler2 is None:  # this indicates the `fit()`
        min_s, max_s = q1 + 0.001, 2.186
        scaler2 = MinMaxScaler(feature_range=(min_s, max_s))
        # min_s and max_s are required to be fit by scaler for consistency between train and test sets
        scaler2.fit(np.array(second + [min_s, max_s]).reshape(-1, 1))