Subtracting Values from the same column into new column based on dates

Hi Evan_Power_Bi ,

Having already seen the video, if any material corresponds to a unique date and your expected output is such, try this calculation column.

Diff_S = 
VAR _date = 'Table'[Date]
VAR _material = 'Table'[Material]
VAR _cur_s =
    CALCULATE (
        MAX ( 'Table'[S] ),
        FILTER ( 'Table', 'Table'[Date] = _date && 'Table'[Material] = _material )
    )
VAR _pre_date =
    CALCULATE (
        MAX ( 'Table'[Date] ),
        FILTER ( 'Table', 'Table'[Material] = _material && 'Table'[Date] < _date )
    )
VAR _pre_s =
    CALCULATE (
        MAX ( 'Table'[S] ),
        FILTER ( 'Table', 'Table'[Date] = _pre_date && 'Table'[Material] = _material )
    ) + 0
VAR _diff =
    IF ( _pre_s <> 0, _cur_s - _pre_s, 0 )
RETURN
    _diff

The PBIX file is attached for reference.

Best Regards,
Gao
Community Support Team

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