Calculate count by category and date- deduct if same date (condition)

[MjoGehri]

Hello guys, im super new on this and i tried to find the solution online without success.

The situation is the following: 

We have many items produced by date, on the example below i have the pallet count and i need it to be deducted from previous if the date is the same:

So basically, if is the same date, the following row should deduct from previous on pallet count.

Is there anyway to accomplish this?

Thank you

[Fowmy · Accepted solution]

@MjoGehri 

You need to add an index column to your table in Power Query first then add the following column using DAX:

New Count = 
VAR __CURRINDEX = 'Table6'[Index] 
VAR __CURRDATE = 'Table6'[Date]
VAR __PREVDATE = MAXX( FILTER( 'Table6', Table6[Index] = __CURRINDEX - 1) , 'Table6'[Date] )      
VAR __CURRAMT = 'Table6'[Count]
VAR __PREVAMT =  MAXX( FILTER( 'Table6', Table6[Index] = __CURRINDEX - 1) , 'Table6'[Count] )    
RETURN
    SWITCH(
        TRUE(),
        __CURRDATE = __PREVDATE , __CURRAMT - __PREVAMT,
        __CURRAMT
    )