def output_res(data, output_cols):
    """Splits dataframe into X and y inputs

        :param data: input data to be split
        :param output_cols: output columns for data, default is none
        :type data: pd.DataFrame
        :type output_cols: list
        :return: the dataframe split into X and y
        :rtype: tuple

    """
    X = data[list(data.columns.difference(output_cols))]
    if len(output_cols) == 1:
        y = data[output_cols[0]]
    else:
        y = data[output_cols]
    return X, y