Reg: WTD

Hi gladies123 

I think you need to build a date table and add a custom weeknum column and a custom year column in it by dax. If you use weeknum function directly, you will get wrong weeknum at the end of the previous year and the beginning of the next year.

For example: 

In my Sample I let week start on Sunday.

2020/12/31,2021/01/01,2021/01/02 are in the same weeknum, but weeknum function will give you 53 in 2020 and 1 in 2021. It's wrong result.

Firstly build a calendar table by dax.

Date = 
ADDCOLUMNS (
    CALENDAR ( DATE ( 2019, 01, 01 ), DATE ( 2021, 12, 31 ) ),
    "Year", YEAR ( [Date] ),
    "Month", MONTH ( [Date] ),
    "WeekNum", WEEKNUM ( [Date], 1 ),
    "WeekDay", WEEKDAY ( [Date], 1 ),
    "MonthName", FORMAT ( [Date], "MMMM" ),
    "DayName", FORMAT ( [Date], "DDDD" )
)

Add calculated columns in it to get correct weeknum and year.

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 WeekYear = 
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])

Build a relationship between this table and your Data table.

Then build a measure to calculate WTD.

WTD =
VAR _SELECTISOYEAR =
    SELECTEDVALUE ( 'Date'[ISO WeekYear] )
VAR _SELECTISOWEEKNUM =
    SELECTEDVALUE ( 'Date'[ISO 8601 WeekNum] )
RETURN
    CALCULATE (
        SUM ( Data[Value] ),
        FILTER (
            ALL ( 'Date' ),
            'Date'[ISO 8601 WeekNum] = _SELECTISOWEEKNUM
                && 'Date'[ISO WeekYear] = _SELECTISOYEAR
        )
    )

Result is sum between 2021/08/15 - 2021/08/21.

 

Best Regards,
Rico Zhou

 

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