Day on Day comparison in a stacked bar chart

[Anonymous]

Hi All,

I have a chart based on the 2 dimensions

1. aggr(Grp,OPP_tDate)
2. Aggr(Only({<OPP_tDate=P(tDate)>}OPP_tDate),OPP_tDate)

Expression is:
sum({<OPP_tDate=P(tDate)>} intEstFees)

where Grp is a list of teams that I need to visualize their performance via a bar chart as below

Here's my LOAD script.

Fact_Table:
LOAD OPP_tDate,Grp,intEstFees 
FROM myFactTableData.qvd (qvd);

MasterCalendar:
LOAD tWeek,tDay, tDate
FROM MasterCalendar.qvd (qvd); 

The bar chart above looks OK, but I need to display additional series to create a day-on-day comparison or "time-on-time" comparison for the previous day / date, but I'm not sure what is the expression I should use or whether I need another dimension...

Can someone pls advise? Thanks...