Calculate expression by previous row

[JJ_masgio]

Hi!
Quite new to DAX.
This is my fact table:

Date (dd-mm-yyyy)	Value
03-06-2023	987
23-06-2023	1112
02-07-2023	1234
12-07-2023	1543

I'm interested in the delta Value across months... but the measure I'm interested in is sush as:
Delta[07] = 1543 - 1112
I mean is the difference between the MAX Value of month 07 and the MAX Value of month 06.
Of course I have a complete Calendar table.
Can you help me in filtering?

Thanks a lot!

[Anonymous · Accepted solution]

Hi @JJ_masgio ,

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

Measure = 
VAR _selyear =
    SELECTEDVALUE ( 'Calendar'[Date].[Year] )
VAR _selmonth =
    SELECTEDVALUE ( 'Calendar'[Date].[MonthNo] )
VAR _curmvalue =
    CALCULATE (
        MAX ( 'Table'[Value] ),
        FILTER (
            ALLSELECTED ( 'Table' ),
            YEAR ( 'Table'[Date] ) = _selyear
                && MONTH ( 'Table'[Date] ) = _selmonth
        )
    )
VAR _premdate =
    EOMONTH ( DATE ( _selyear, _selmonth, 1 ), -1 )
VAR _premvalue =
    CALCULATE (
        MAX ( 'Table'[Value] ),
        FILTER (
            ALLSELECTED ( 'Table' ),
            YEAR ( 'Table'[Date] ) = YEAR ( _premdate )
                && MONTH ( 'Table'[Date] ) = MONTH ( _premdate )
        )
    )
RETURN
    IF (
        ISBLANK ( _premvalue ) || ISBLANK ( _curmvalue ),
        BLANK (),
        _curmvalue - _premvalue
    )

Delta = 
IF (
    ISINSCOPE ( 'Calendar'[Date].[Year] ),
    [Measure],
    SUMX (
        GROUPBY ( 'Calendar', 'Calendar'[Date].[Year], 'Calendar'[Date].[Month] ),
        [Measure]
    )
)

Best Regards