Need Help with DAX Formula to combine rows

rizkus 

Apart from DataNinja777  solution, Alternatively, you can use below tiny DAX code

Value Measure = 
VAR _Rank = 
RANKX( ALL( 'Table'[Segment]),CALCULATE( SUM( 'Table'[ValueMeasure])),,DESC)
VAR _Result = 
IF(
    _Rank =1,
    CALCULATE( SUM( 'Table'[ValueMeasure]), ALL( )
    ) ,BLANK()
)
RETURN
_Result

Below screenshots

when you select Segment A

Hopt it helps

Regards

sanalytics

Hello rizkus 

Thanks for your question!
I have recreated your scenario and here’s the full explanation. 

DataTable:

RankTable:

TopSegmentTotal :=
IF (
    ISINSCOPE ( 'DataTable'[ID] ),
    VAR CurrentID =
        SELECTEDVALUE ( 'DataTable'[ID] )
    VAR TopRankForID =
        CALCULATE (
            MIN ( 'RankTable'[Rank] ),
            FILTER ( ALL ( 'DataTable' ), 'DataTable'[ID] = CurrentID )
        )
    VAR CurrentSegmentRank =
        MIN ( 'RankTable'[Rank] )
    VAR TotalForID =
        CALCULATE (
            SUM ( 'DataTable'[Value Measure] ),
            FILTER ( ALL ( 'DataTable' ), 'DataTable'[ID] = CurrentID )
        )
    RETURN
        IF (
            ISFILTERED ( 'DataTable'[Segment] )
                && SELECTEDVALUE ( 'DataTable'[Segment] ) = "A",
            TotalForID,
            IF ( CurrentSegmentRank = TopRankForID, TotalForID )
        )
)

Why the Difference

• In your screenshot, Segment B had only one row (300), so the total was 300.

• In my dataset, Segment B has two rows (200 + 300), so the total is 600.

• The measure is correct, it always sums all values for the same ID and shows the total only on the top‑ranked segment.

Filtering Behavior

• If you filter Segment B, the measure shows the total (600).

• If you filter Segment A, the measure shows blank (unless you allow it to return the total for A).

• If you want to show the raw row (300) instead of the total, use Value Measure directly and filter to that row.

Conclusion

• Use Value Measure if you want to show raw rows (200 and 300 separately, or just 300).

• Use TopSegmentTotal if you want to show the combined total (600) for the top segment.

• Both are correct , it depends on whether you want to display raw values or the calculated total.

• Slicers make it easy to toggle between segments and see how the measure behaves under filter

• Slicer showing TopSegment TotalValue Measure for Segment B only