How to calculate difference in previous row?

[SSIAB]

I have a date column that is sorted by week. I have another coulmn labeled PC valued with data values. How can I calculate to see the difference between each week in the PC column? Here is a screen shot below. 

[Irwan · Accepted solution]

Hello @SSIAB 

please check if this will acommodate your need.

1. create calculated column for calculating week as you want to see weekly value difference

Week = WEEKNUM('Table'[Date],21) //put 21 for ISOWEEKNUM or depend on what you need

2. find previous week value then substract current week with previous week

Diff =

var _PreviousValue = MAXX(FILTER('Table','Table'[Week]<EARLIER('Table'[Week])),'Table'[Value]) //find previous week value

Return

'Table'[Value]-_PreviousValue

The first value return as 149 as there is no previous value, otherwise if you want to make it zero at the very first line then use this dax instead:

Diff =

var _PreviousValue = MAXX(FILTER('Table','Table'[Week]<EARLIER('Table'[Week])),'Table'[Value]) //find previous week value

Return

IF(

    'Table'[Week]=MIN('Table'[Week]),

    0,

    'Table'[Value]-_PreviousValue

)

Hope this will help you.

Thank you.