Find difference between the 2 rows of column based on another column criteria

Hi axk180022 

According to your statement, I know you want to show absolute Gen Difference. And you will filter your table to show first 2 date for each serialid, you just want show difference in 1st latest date and difference in 2nd latest date will show blank. Here I suggest you build a table visual and create a measure to achieve your goal. Measure could be dynamic.

My Sample:

Rank is a calculated column.

Rank = RANKX(FILTER('Table','Table'[serialid]=EARLIER('Table'[serialid])),'Table'[Dates],,DESC,Dense)

Build a table visual and filter visual by rank column to show items when value is less than or equal to 2.

Measure:

Gen Difference = 
VAR _RANK1GenHours =
    CALCULATE (
        SUM ( 'Table'[GenHours] ),
        FILTER (
            ALL ( 'Table' ),
            'Table'[serialid] = MAX ( 'Table'[serialid] )
                && 'Table'[Rank] = 1
        )
    )
VAR _RANK2GenHours =
    CALCULATE (
        SUM ( 'Table'[GenHours] ),
        FILTER (
            ALL ( 'Table' ),
            'Table'[serialid] = MAX ( 'Table'[serialid] )
                && 'Table'[Rank] = 2
        )
    )
RETURN
    IF (
        SUM ( 'Table'[Rank] ) = 1,
        ABS ( _RANK1GenHours - _RANK2GenHours ),
        BLANK ()
    )

Result is as below.

Best Regards,
Rico Zhou

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