in DAX for values in current period check occurrences in previous dates (including selected period)

[Anonymous]

I have following table:

id  date

1a  01.01.19

1a  02.01.19

2a  03.01.19

3a  04.01.19

4a  02.02.19

4a  03.02.19

2a  04.02.19

3a  05.02.19

I'm trying to calculate amount of distinct ID's in selected period which has appeared more than 1 time in the period earlier to the latest date in selected period

So selecting Jan'2019 should return - 1 ("1a" counted, "2a" and "3a" skipped, since only 1 time appeared)

Selecting Feb'2019 returns 3 ("2a", "3a" and "4a" counted since appeared >1 time in Jan/Feb, "1a" is skipped since not appeared in selected period)

[az38]

Hi @Anonymous 

try the next technique

create 2 columns:

1.

DateKey = FORMAT([date];"YYYY-MM")

2. 

CountBeforePeriod = 
 CALCULATE(COUNTROWS('Table');ALL('Table');'Table'[id]=EARLIER([id]);'Table'[date]<=EOMONTH(EARLIER([date]);0))

then create a final measure

Measure = calculate(DISTINCTCOUNT('Table'[id]);ALLEXCEPT('Table';'Table'[DateKey]);'Table'[CountBeforePeriod]>1)

do not hesitate to give a kudo to useful posts and mark solutions as solution

[TomMartens · Accepted solution]

Hey @Anonymous 

first I created a dedicated Calendar Table (this is always a best practice), I used this DAX statement (a very simplified one) to create this table:

Calendar = 
    ADDCOLUMNS(
        CALENDAR("2019-01-01" , "2019-02-28") 
        , "Year-Month" , FORMAT(''[Date] , "YYYY-MM")
    )

Then I created a relationship between both tables like this:

Finally, I created this measure:

Measure = 
    SUMX(
        VALUES('Table'[id])
        , 
        var _maxdate = MAX('Calendar'[Date])
        var _count = 
            CALCULATE(COUNT('Table'[id]) 
            , FILTER(
                ALL('Calendar'[Date]) , 
                'Calendar'[Date] <= _maxdate 
                -- uncomment if you have more than one year
                -- && YEAR('Calendar'[Date]) = YEAR(_maxdate)
                )
            )
        return
        IF(_count >  1 , 1 , BLANK())
    )

This allows to create this table visual (be aware that it's also a good idea to use the columns from the Calendar table):

Hopefully, this is what you are looking for.

Regards,

Tom

[Anonymous]

@TomMartens thanks, works perfectly.

Maybe you are also aware of how to handle the following issue (just created new post 🙂)  https://community.powerbi.com/t5/Desktop/in-DAX-count-distinct-values-from-previous-dates-missing-in...