Forum Discussion
Recursive Calculation and Forecast measure
Hi murillocosta
Such fully recursive problems cannot be handled by DAX straight forward. A helper table that suits your case shall be needed to handle the recursion. The solution is a bet difficult to understand and it should be carefully design to suit each case independently (cannot be generalized) nevertheless, what ever the chosen details of the solution, the general idea remains the same.You need to import the Fibonacci table as is and use the DAX as is. However, your real data might not be as I expected, therefore some changes might be required.
Please note that such reports should have limited flexibility in terms of the columns used to slice. Slicing by different column(s) might require changing the code. You need to understand that this is a limitation of the DAX language for the time being, hopping future updates will curry new features of the language such as loops that can help performing recursive calculations much more easier.
Also Please note that there is a rounding error with this method and the results shall not be 100% accurate.
Please refer to the sample file with the solutionForecast Count = VAR W = CALCULATE ( MAX ( 'Table'[Year Week Sort] ), REMOVEFILTERS ( ) ) -- with real data would be VAR LastDateWithData 'Table'[Date] and then VAR W = YEAR ( LastDateWithData ) * 100 + WEEKNUM ( LastDateWithData ) VAR CW = MAX ( 'Date'[Year Week Sort] ) VAR S4 = CALCULATE ( [CounRef], 'Date'[Year Week Sort] = W, ALLSELECTED ( ) ) VAR S3 = CALCULATE ( [CounRef], 'Date'[Year Week Sort] = W - 1, ALLSELECTED ( ) ) VAR S2 = CALCULATE ( [CounRef], 'Date'[Year Week Sort] = W - 2, ALLSELECTED ( ) ) VAR S1 = CALCULATE ( [CounRef], 'Date'[Year Week Sort] = W - 3, ALLSELECTED ( ) ) VAR SelectedWeeks = ALLSELECTED ( 'Date'[Year Week Sort] ) VAR WeeksOnAndBefore = FILTER ( SelectedWeeks, 'Date'[Year Week Sort] > W && 'Date'[Year Week Sort] <= CW ) VAR Ranking = COUNTROWS ( WeeksOnAndBefore ) RETURN SUMX ( FILTER ( FibonacciTable, FibonacciTable[Index] = Ranking ), FibonacciTable[Value1] * S1 + FibonacciTable[Value2] * S2 + FibonacciTable[Value3] * S3 + FibonacciTable[Value3] * S4 )murillocosta
Here you go
Hey tamerj1, just one more question. If I need to change the average from 4 to n.....how would you update the fibonacci table values????is there any place you can get it from?
Hi murillocosta
Attached your sample file updated with the dynamiuc solution
Total Outbound Final 2 =
VAR Periods = [Number of Periods Value]
VAR TotalOutBound = [Total Outbound]
VAR W = CALCULATE ( MAX ( 'SUMMARIZE'[Week Rank] ), 'SUMMARIZE'[Total Outbound] <> 0, REMOVEFILTERS ( ) )
VAR CW = MAX ( 'SUMMARIZE'[Week Rank] )
VAR SelectedWeeks = CALCULATETABLE ( VALUES ( 'SUMMARIZE'[Week Rank] ), ALLSELECTED ( ) )
VAR WeeksOnAndBefore =
FILTER(
SelectedWeeks,
'SUMMARIZE'[Week Rank] > W && 'SUMMARIZE'[Week Rank] <= CW
)
VAR CurrentIndex = COUNTROWS ( WeeksOnAndBefore )
VAR T1 = SELECTCOLUMNS ( GENERATESERIES ( 1, Periods, 1 ), "@ValueInex", [Value] )
VAR T2 =
ADDCOLUMNS (
T1,
"@Value",
VAR ValueIndex = [@ValueInex]
RETURN
CALCULATE ( [Total Outbound], 'SUMMARIZE'[Week Rank] = W + ValueIndex - Periods, ALLSELECTED ( ) )
)
VAR Result =
SUMX (
T2,
VAR CurrentValue = [@Value]
VAR FibTable =
FILTER (
Fibonacci_Table,
Fibonacci_Table[Index] = CurrentIndex
&& Fibonacci_Table[Period Index] = Periods
&& Fibonacci_Table[Value Index] = [@ValueInex]
)
VAR FibValue = MAXX ( FibTable, Fibonacci_Table[Value] )
RETURN
CurrentValue * FibValue
)
RETURN
Result + TotalOutBound
Hello, tamerj1
I stumbled upon this post while searching for a solution similar to the one you provided. I need to calculate data based on previously calculated data using the same metric. Your solution is truly impressive! Thank you for sharing it.
Now, I'm working on adapting it to my needs, and I'm hopeful that I'll manage to make it work. Regarding the Fibonacci_Table, is that the only method available for performing such calculations?
Hi vitorcampos
Glad that you found that helpful.
Regarding your question, to be honest I have not been following up on this subject for some time. I'm not aware of any other method. In fact he Fibonacci table is some that I have invented couple of years ago to tackle this issue of recursion following mathematical approach.
As far as I know Greg_Deckler was following up on this subject since long time ago. I believe no one can advise on this subject better than he can do.tamerj1 vitorcampos Yeah, true recusion is a pain and doesn't work: Previous Value (“Recursion”) in DAX – Greg Deckler
That article contains a bunch of links to various methods I've tried.
Thank you . It's really helpful, I will use this for my projects for recursive calculations. I always try to perform this type of calculation on dbt which is the tool I use for transformation before pulling the data into PBI but some case I only have the data uploaded to PBI.
I think you uploaded the wrong file. Could please send my sample file updated?
Thanks
murillocosta
Apologies for that. The attachment in my previous reply has been updated. Please check.
Hi tamerj1
Would you be able to help me calculate the "Total Outbound Final 2" for the past records as well instead of just repeating the "Total Outbound" as below?
The ideia is to create a compararion of the actual spend vs forecast that was calculated in the past.
I tried it today for couple of hours but it seems that it will require to change Fibonacci table.
What do you think?
For example:
Let suppose we pick 7 for the "Number of Period" so the first 7 rows we would need to repeat the Total Outbound (as we won't have enough data to calculate average) and from the eight row we start calculating it recursively as it's already doing for forecast.
Thanks
Thanks
