每日每个股票持仓市值表

        Returns:
            pd.DataFrame -- 市值表

def market_value(self):
        """每日每个股票持仓市值表

        Returns:
            pd.DataFrame -- 市值表
        """
        if self.account.daily_hold is not None:
            if self.if_fq:

                return (
                    self.market_data.to_qfq().pivot('close').fillna(
                        method='ffill'
                    ) * self.account.daily_hold.apply(abs)
                ).fillna(method='ffill')
            else:
                return (
                    self.market_data.pivot('close').fillna(method='ffill') *
                    self.account.daily_hold.apply(abs)
                ).fillna(method='ffill')
        else:
            return None