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ilcaa72's avatar
ilcaa72
Helper IV
8 years ago
Solved

Reference Previous Value in adjacent column

in Power BI Desktop... i have a Column that has prices, and I want to create a new column that shows a + sign or - sign, "if current value > previous value then "+", if current value < previous value then "-".  Its easy to do in Excel, how do I accomplish this in BI Desktop

 

thanks

 

IN EXCEL, B2 =IF(A1 >A2, "-","+")

 

Need Help
  • Stachu's avatar
    Stachu
    8 years ago

    I may be simplifying it, but DAX calculates the whole column at the same time, the visible order in the pivot is not really relevant for the calculation

    Regardless - this should work, it looks up the Index that is lower than current index and where price is different than current price

    =
VAR CurrentIndex = INTC[Index]
VAR CurrentPrice = INTC[Prices]
VAR PreviousIndex  = CALCULATE(MAX(INTC[Index]),FILTER(ALL(INTC),AND(INTC[Index]<CurrentIndex,INTC[Prices]<>CurrentPrice)))
VAR PreviousPrice = CALCULATE(SUM(INTC[Prices]),FILTER(ALL(INTC),INTC[Index]=MAX(PreviousIndex,1)))	//gets previous price
VAR Delta = INTC[Prices]-PreviousPrice	//calculates the delta
RETURN
IF(Delta<0,"-",IF(Delta>0,"+",BLANK()))




8 Replies

  • Phil_Seamark's avatar
    Phil_Seamark
    Microsoft Employee
    8 years ago

    Hi ilcaa72

     

    You can do it, but because of the way data is stored in the data model, you need to use a slightly different syntax.

     

    Do you have an index column, or something with sequential numbers or dates?

  • Zubair_Muhammad's avatar
    Zubair_Muhammad
    Community Champion
    8 years ago

    Hi ilcaa72

     

    Try this.

     

    First Add an Index Column from the Query Editor.

     

    Then you can use this Column

     

    Column =
VAR NextRow =
    CALCULATE (
        SUM ( Table1[Prices] ),
        FILTER ( Table1, Table1[Index] = EARLIER ( Table1[Index] ) + 1 )
    )
RETURN
    IF ( Table1[Prices] > NextRow, "-", "+" )
    • ilcaa72's avatar
      ilcaa72
      Helper IV
      8 years ago

      I am using this formula. I almost have it.  BUT, I want to reference the previous value in the same column of my Calculated Field.

       

      I am writing the calculated column in Column [Trade] but intellisense doesnt give it as an option.  I need to reference the previous value of the same column.  Whats the proper syntax? 
       

      my formula should include these 3 conditions...

      if current Price > previous price, +

      if current Price < previous price, -

      if current price = previous Price, previous row Column Value

       

      i have this formula, but I cant reference same column name as the one i am in writing formula (Trade).  Can "EARLIER" be used alone (see last line, last condition)

       

      Trade = VAR NextRow =   CALCULATE ( SUM ( INTC[Prices] ),
        FILTER ( INTC, INTC[Index] = EARLIER ( INTC[Index] ) -1 )    )
        RETURN   NextRow & " : " &
        IF ( INTC[Prices] > NextRow, "+", IF ( INTC[Prices] < NextRow, "-", IF(INTC[Prices] = NextRow, EARLIER(INTC[Trade],1))))

       

       

      • Stachu's avatar
        Stachu
        Community Champion
        8 years ago

        I'm not sure how your last criteria (equal prices) would work as the column would have to iterate itself, otherwise this syntax should work:

        =
        VAR PrevRowIndex = MAX(INTC[Index]-1,1) //handles the first row
        VAR PrevPrice = CALCULATE(SUM(INTC[Prices]),FILTER(ALL(INTC),INTC[Index]=PrevRowIndex)) //gets previous price
        VAR Delta = INTC[Prices]-PrevPrice //calculates the delta
        RETURN
        IF(Delta<0,"-",IF(Delta>0,"+","~"))



    • Anonymous's avatar
      Anonymous
      Not applicable
      6 years ago

      Hi,

       

      How to refer previous adjacent cell value in Matrix.

       

      Note: values in Matrix is Dax Measure.

  • TomMartens's avatar
    TomMartens
    Super User
    8 years ago

    Hey ilcaa72

     

    In comparison to using Excel the same needs a little more sophisticated approach in Power BI.

     

    Here you will find a PBIX file

     

    The approach here is to find a Value of the previous row,

    Basically the pattern I use is to find the MAX Date of group of rows where all the dates in that group are smaller than the current date, I call that date previousTransactiondate. In my example it's a variable in the calculation for the measure "Previous Value".

    Then I use the date I found to determine the previous value.

    This is how the measure looks like:

    Previous Value = 
var currentCustomer = FIRSTNONBLANK('Simple Facts'[Customer],1)
var currentTransactionDate = FIRSTNONBLANK('Simple Facts'[TransActionDate],1)
var previousTransactiondate = 
CALCULATE(
    MAX('Simple Facts'[TransActionDate])
    ,FILTER(ALL('Calendar'[Date])
        ,'Calendar'[Date] < currentTransactionDate
    )
)
var previousvalue = 
CALCULATE(
    SUM('Simple Facts'[Value])
    ,FILTER(ALLSELECTED('Simple Facts')
        ,'Simple Facts'[TransActionDate] = previousTransactiondate
        && 'Simple Facts'[Customer] = currentCustomer
    )
)
return
previousvalue

     

    Please be aware that my example also contains an extra twist, the customer, this is maybe not necessary in your situation.
    Also consider that a ROW index (a ROW identifier) maybe not be contiguous to applied slicer.
    Nevertheless it's always a good idea to have a rownumber that uniquely identifies a row in each of your tables.


    In my example file this unique identifier is the column value that is automatically created by the formula GENERATESERIES, but you do not need to consider this fact for your case :-) This is just due to an experiment to create sample data.

     

    Hopefully this gives you an idea.

     

    Regards

    Tom