def _get_r(cls, df, column, shifts):
        """ Get rate of change of column

        :param df: DataFrame object
        :param column: column name of the rate to calculate
        :param shifts: days to shift, accept one shift only
        :return: None
        """
        shift = cls.to_int(shifts)
        rate_key = '{}_{}_r'.format(column, shift)
        df[rate_key] = df[column].pct_change(periods=-shift) * 100
Get rate of change of column

        :param df: DataFrame object
        :param column: column name of the rate to calculate
        :param shifts: days to shift, accept one shift only
        :return: None