DAX Logic for Calculating Rolling Sum

[andy291086]

Hi Team, 

I am new to Power BI and DAX. I had been assigned to convert an Excel report into Power BI which has the following calculations. 

I am stuck up with the calculations for Behind , which is based on the excel formula , Prior Behind Days + ( Target Days - Rolling Average Days) / Weeks left. Behind Days for Week 1 is 0 . 

For .e,g, for Week 3, the behind is calculated as 0.5 + (350 - 295.67)/49 = 1.6, 

Can you please help ?

Cheers, 

Andy

[Anonymous · Accepted solution]

Hi @andy291086 ,

I created a sample pbix file(see the attachment) for you, please check if that is what you want.

Week Number = VALUE(RIGHT('Table'[Week], LEN('Table'[Week]) - 5))

Column = 
VAR _preweek =
    CALCULATE (
        MAX ( 'Table'[Week Number] ),
        FILTER ( 'Table', 'Table'[Week Number] < EARLIER ( 'Table'[Week Number] ) )
    )
VAR _prewbdays =
    CALCULATE (
        MAX ( 'Table'[Behind Days] ),
        FILTER ( 'Table', 'Table'[Week Number] = _preweek )
    )
RETURN
    _prewbdays + ( 'Table'[Target Days] - [Rolling Average - Days] ) / 'Table'[Weeks Left]

Best Regards