选取日期(一般用于分钟线)

        Arguments:
            day {[type]} -- [description]

        Raises:
            ValueError -- [description]

        Returns:
            [type] -- [description]

def select_day(self, day):
        """选取日期(一般用于分钟线)

        Arguments:
            day {[type]} -- [description]

        Raises:
            ValueError -- [description]

        Returns:
            [type] -- [description]
        """

        def _select_day(day):
            return self.data.loc[day, slice(None)]

        try:
            return self.new(_select_day(day), self.type, self.if_fq)
        except:
            raise ValueError('QA CANNOT GET THIS Day {} '.format(day))