topic Re: Cummulative Prev Change in DAX Commands and Tips

Cummulative Prev Change

Anonymous — Tue, 05 Nov 2019 19:07:11 GMT

Good afternoon

I am struggling with a DAX formula, and will appreciate some help

Want to create a formula for "Cummulative Prev Change" as per screenshot and following conditions

1) First two rows have to be zero

2) from 3rd row, the formula should get PreviousVersions's "Requested Value" + PreviousVersions's "Cummulative Prev Change" if

I tried following formula, to no effect 😞

CummulativePrevChange2 = IF(PA_KEY[Version]>1,LOOKUPVALUE(PA_KEY[RequestedValue],PA_KEY[Version],PA_KEY[Version]-1,PA_KEY[PA#],PA_KEY[PA#]),0)

Attached are the sample file and screenshot of how the column should calculate values...

PowerBI File

How it should look like

Thank you in advance for any advise 🙂

Re: Cummulative Prev Change

Nathaniel_C — Tue, 05 Nov 2019 22:48:13 GMT

Re: Cummulative Prev Change

Anonymous — Wed, 06 Nov 2019 13:37:27 GMT

thank you Nathan,

Kindly can you share the DAX for your column?

thank you

-Usman

Re: Cummulative Prev Change

Nathaniel_C — Wed, 06 Nov 2019 14:18:00 GMT

Hi Anonymous
The solution at this point is two columns.

Let me know if you have any questions.

If this solves your issues, please mark it as the solution, so that others can find it easily. Kudos are nice too.
Nathaniel

Cumulative = var _curIndex =PA_KEY[Index] var _minIndex = CALCULATE(MIN(PA_KEY[Index]),ALLEXCEPT(PA_KEY,PA_KEY[PA#]),PA_KEY[Index]<_curIndex) return IF(_curIndex = _minIndex || _curIndex = _minIndex+1,BLANK(), CALCULATE(sum(PA_KEY[RequestedValue]),ALLEXCEPT(PA_KEY,PA_KEY[PA#]),PA_KEY[Index]=_curIndex -1))

Cumulative and previous = VAR _curIndex = PA_KEY[Index] //Get current Index from this row VAR _minIndex = CALCULATE ( MIN ( PA_KEY[Index] ), ALLEXCEPT ( PA_KEY, PA_KEY[PA#] ), PA_KEY[Index] < _curIndex ) //Get minimum index for this PA# VAR _prev3 = CALCULATE ( SUM ( PA_KEY[Cumulative] ), ALLEXCEPT ( PA_KEY, PA_KEY[PA#] ), PA_KEY[Index] = _curIndex - 1 ) // Get the previous row amount from the Cumulative column RETURN IF ( //Return a blank if the current index is equal to the first two rows of this PA# else do the calc and add the previous row from the Cumulative column _curIndex = _minIndex || _curIndex = _minIndex + 1, BLANK (), CALCULATE ( SUM ( PA_KEY[RequestedValue] ), ALLEXCEPT ( PA_KEY, PA_KEY[PA#] ), PA_KEY[Index] = _curIndex - 1 ) + _prev3 )

Re: Cummulative Prev Change

Nathaniel_C — Wed, 06 Nov 2019 14:28:38 GMT

Hi Anonymous , jdbuchanan71 ,
You are in luck! This is from jdbuchanan71 , one column and much simpler code.

Hi Nathaniel, The problem I see is how to determine the order of the lines. I know you added an index but will the rows always come out of the source in the right order? I would verify that with the original poster. If the index can be added safely then this code should work. Column = VAR _MinIndex = CALCULATE ( MIN ( PA_KEY[Index] ), ALLEXCEPT ( PA_KEY, PA_KEY[PA#] ) ) VAR _RowIndex = [Index] RETURN CALCULATE ( SUM ( PA_KEY[RequestedValue] ), ALLEXCEPT ( PA_KEY, PA_KEY[PA#] ), PA_KEY[Index] > _MinIndex && PA_KEY[Index] < _RowIndex ) ========================= We don't need to do any checking for the first 2 rows because the filters PA_KEY[Index] > _MinIndex && PA_KEY[Index] < _RowIndex take care of it. On index line 5 for example. _MinIndex = 4 _RowIndex = 5 We ask for the sum of PA_KEY[RequestedValue] where the Index is > 4 AND < 5. No such lines so we get nothing. On Index line 7 we as for the sum of [RequestedValue] where the Index > 4 AND < 7. We get the sum of Index 5 and 6

Nathaniel

Re: Cummulative Prev Change

jdbuchanan71 — Wed, 06 Nov 2019 14:58:44 GMT

Anonymous

Just this portion is the measure and it relies on the index column Nathaniel_C added to your sample table.

Column = VAR _MinIndex = CALCULATE ( MIN ( PA_KEY[Index] ), ALLEXCEPT ( PA_KEY, PA_KEY[PA#] ) ) VAR _RowIndex = [Index] RETURN CALCULATE ( SUM ( PA_KEY[RequestedValue] ), ALLEXCEPT ( PA_KEY, PA_KEY[PA#] ), PA_KEY[Index] > _MinIndex && PA_KEY[Index] < _RowIndex )

Are you able to add an index column to your source data that will properly order the lines?

Re: Cummulative Prev Change

Anonymous — Wed, 06 Nov 2019 19:11:24 GMT

thank you JDBuchanon, and Nathan for your replies

Adding an index (order by) will make query quite slow.

Is there any other suggestions without adding index column please ?

thank you again

-Usman

Re: Cummulative Prev Change

jdbuchanan71 — Wed, 06 Nov 2019 19:17:58 GMT

Anonymous

If the data always come into the model in the correct order you can just add an index row in the query editor the way Nathaniel_C did.

Without an index column, what it the logic to determine "previous row"? Keep in mind that PowerBI does not understand "this row is the row before the row I am on" the way excel does. That is why we need an index column or some other logic to tell PowerBI how to search the entire table and find the previous rows. Also, what is your data source for the information?

Re: Cummulative Prev Change

Anonymous — Wed, 06 Nov 2019 19:40:16 GMT

thanks for your reply

"PA_Key" and "Invoice Line" is the unique key/index; e.g. "1043-1-1" which shows "Purchase Order-Version#-Invoice Line#" respectively

Can we somehow use the original table to do it, or would we have to add a new index and use order by clause, to always order them by Purchase Order, Invoice Line#, Version # ?

thank you

Re: Cummulative Prev Change

jdbuchanan71 — Wed, 06 Nov 2019 19:53:23 GMT

The problem with using the original table is you don't know what order the lines are going to come in unless you give it an order by. You could add the index on the SQL side as well, something like this.

SELECT PA_Key, Version, [Invoice LINE], CONTRACTLINEVALUE, REQUESTEDVALUE, PA#, ROW_NUMBER() OVER( ORDER BY ( SELECT 0 ) ) AS RowIndex FROM Table ORDER BY PA_Key, Version, [Invoice LINE]

Re: Cummulative Prev Change

Anonymous — Thu, 07 Nov 2019 20:58:59 GMT

Thank you JDBuchanan and Nathan, for all you help.

Much appreciated 🙂