Subtract Values per week

[Syndicate_Admin]

Hello!

I have a chart that has the x-axis the weeks and as a value the safety stock. I need you to see in the graph the difference between one week and another.

For example. Week 30 there are 399 and week 31 there are 398. So, I need to see in week 31 the value of the difference, that is: -1. So on.

Thanks a lot!

[Anonymous · Accepted solution]

Hi @Syndicate_Admin 

At first, try my code to build a date table. If you use weeknum, you will get confused at the begining of next year.

For example, 2020/12/31 and 2021/01/01 are in the same week, but weeknum will show you 53 and 1. That's incorrect and will make our calculate difficult. 

Date table:

Date =
ADDCOLUMNS (
    CALENDARAUTO (),
    "Year", YEAR ( [Date] ),
    "Month", MONTH ( [Date] ),
    "Weeknum", WEEKNUM ( [Date], 2 ),
    "YearMonth",
        YEAR ( [Date] ) * 100
            + MONTH ( [Date] )
)

Add calculated columns:

ISO 8601 WeekNum = 
VAR _COUNT0 =
    CALCULATE (
        COUNTROWS ( 'Date' ),
        FILTER (
            'Date',
            'Date'[Year] = EARLIER ( 'Date'[Year] )
                && 'Date'[WeekNum] - 1 = 0
        )
    )
VAR _BASENUM1 =
    IF ( _COUNT0 < 7, 'Date'[WeekNum] - 1, 'Date'[WeekNum] )
VAR _ISO_8601_WeekNum =
    IF (
        WEEKDAY ( DATE ( 'Date'[Year] - 1, 01, 01 ) ) <> 1
            && 'Date'[Year] = 'Date'[Year]
            && _BASENUM1 = 0,
        WEEKNUM ( DATE ( MIN ( 'Date'[Year] ), 12, 31 ), 1 ) - 1,
        _BASENUM1
    )
RETURN
    _ISO_8601_WeekNum

ISO_Year = 
VAR _COUNT0 =
    CALCULATE (
        COUNTROWS ( 'Date' ),
        FILTER (
            'Date',
            'Date'[Year] = EARLIER ( 'Date'[Year] )
                && 'Date'[WeekNum] - 1 = 0
        )
    )
VAR _BASENUM1 =
    IF ( _COUNT0 < 7, 'Date'[WeekNum] - 1, 'Date'[WeekNum] )
RETURN
IF(_BASENUM1 = 0,'Date'[Year] -1,'Date'[Year])

ISO YearWeekNum = 'Date'[ISO_Year]*100+'Date'[ISO 8601 WeekNum]

Build a relationship between your data table and this calendar date table by date column.

Create a measure as below.

Diff =
VAR _CurValue =
    CALCULATE ( SUM ( 'Sample'[Value] ) )
VAR _LastISOYearWeekNum =
    MAXX (
        FILTER (
            ALL ( 'Date' ),
            'Date'[ISO YearWeekNum] < MAX ( 'Date'[ISO YearWeekNum] )
        ),
        'Date'[ISO YearWeekNum]
    )
VAR _LastValue =
    CALCULATE (
        SUM ( 'Sample'[Value] ),
        FILTER ( ALL ( 'Date' ), 'Date'[ISO YearWeekNum] = _LastISOYearWeekNum )
    )
RETURN
    _CurValue - _LastValue

Result is as below.

Best Regards,
Rico Zhou

If this post helps, then please consider Accept it as the solution to help the other members find it more quickly.

[amitchandak]

@Syndicate_Admin , You need an independent week or year week table, with Rank on Year week.

New column in Date or Ywar week column

new columns
Week Start date = 'Date'[Date]+-1*WEEKDAY('Date'[Date],2)+1
Week End date = 'Date'[Date]+ 7-1*WEEKDAY('Date'[Date],2)
Week Rank = RANKX(all('Date'),'Date'[Week Start date],,ASC,Dense)
OR
Week Rank = RANKX(all('Date'),'Date'[Year Week],,ASC,Dense) //YYYYWW format

measures
This Week = CALCULATE(sum('Table'[Qty]), FILTER(ALL('Date'),'Date'[Week Rank]=max('Date'[Week Rank])))
Last Week = CALCULATE(sum('Table'[Qty]), FILTER(ALL('Date'),'Date'[Week Rank]=max('Date'[Week Rank])-1))