Percentage Difference Formula Help

[MT54]

Hi, 

I have searched the forums but didn't find anything that was what I'm trying to do and my attempts to change other formulae and use the quick measures haven't worked. I'm trying to create the two columns shown in the table below "Difference" and % Difference, I've populated these with my expected values already but can't do this using Power BI.

The step column is used as a counter and first "Step" is always 1 and the last "Step" is always 6.

For the "Difference" column, every step except 6 and 1 needs to subtract its value from the previous step "value" (1 just equals 0 and 6 needs to subtract from 1's value to get the overall change).  

For the "% Difference" column, every step except 6 and 1 should be Difference divided by the previous step "Value"  (1 just equals 0 and 6 needs to divide by 1's value to get the overall % diff).  

Please can anyone help? I'm running out of ideas!

Thanks, Mike

Category	Step	Value	Difference	% difference
A	1	100	0	0%
A	2	105	5	5%
A	3	106	1	1%
A	4	80	-26	-25%
A	6	90	-10	-10%
B	1	50	0	0%
B	2	55	5	10%
B	3	40	-15	-27%
B	4	60	20	50%
B	5	80	20	33%
B	6	90	40	80%

[Anonymous · Accepted solution]

Hi @MT54 ,

I suggest you to try code as below to create calculated columns.

Difference = 
VAR _1 = 0
VAR _2to5 =
    CALCULATE (
        SUM ( 'Table'[Value] ),
        FILTER (
            ALLEXCEPT ( 'Table', 'Table'[Category] ),
            'Table'[Step]
                = EARLIER ( 'Table'[Step] ) - 1
        )
    )
VAR _6 =
    CALCULATE (
        SUM ( 'Table'[Value] ),
        FILTER ( ALLEXCEPT ( 'Table', 'Table'[Category] ), 'Table'[Step] = 1 )
    )
RETURN
    IF (
        'Table'[Step] = 1,
        _1,
        IF ( 'Table'[Step] = 6, 'Table'[Value] - _6, 'Table'[Value] - _2to5 )
    )

% difference = 
VAR _1 = 0
VAR _2to5 =
    CALCULATE (
        SUM ( 'Table'[Value] ),
        FILTER (
            ALLEXCEPT ( 'Table', 'Table'[Category] ),
            'Table'[Step]
                = EARLIER ( 'Table'[Step] ) - 1
        )
    )
VAR _6 =
    CALCULATE (
        SUM ( 'Table'[Value] ),
        FILTER ( ALLEXCEPT ( 'Table', 'Table'[Category] ), 'Table'[Step] = 1 )
    )
RETURN
    IF (
        'Table'[Step] = 1,
        _1,
        DIVIDE ( 'Table'[Difference], IF ( 'Table'[Step] = 6, _6, _2to5 ) )
    )

Result is as below.

Best Regards,
Rico Zhou

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