Calculating single values from cumulative data in Power BI - powerbi

Question

In my sales table I would like to change cumulative values into single values. Here is sample data from my table.
I created a measure that as far as I know should works for this.
sales_single_values = VAR current_sales = SUM('sales'[sales cumulative]) VAR prev_sales SUM('sales'[sales cumulative]) - CALCULATE( current_sales, 'sales'[period] = 'sales'[period] - 1) Return IF(ISBLANK(prev_sales), BLANK(), current_sales - prev_sales)
But unfortunately the final result on the chart is still the same as I used cumulative values, not single ones. Any ideas what should I change in my measure?
Expected values would be:
Period 1: 4
Period 2: 2
Period 3: 7

Answer 1

As a measure, something like:
sales_single_values =
var prev = max('sales'[period]) - 1
var prev_sales = CALCULATE( SUM('sales'[sales cumulative]), 'sales'[period] = prev)
Return
sum(sales[sales cumulative]) - prev_sales
But this seems like more of a modeling transformation, so do it in PQ, or with a calculated column, like
current sales =
var prev = calculate( max('sales'[period]) ) - 1
var prevSales = calculate( sum(sales[sales cumulative]), all(sales), sales[period] = prev)
return
sales[sales cumulative]-prevSales