Bar Chart / Date Calculation

Thanks v-juanli-msft

There is a more elegant solution by Marco Russo.

Step 1:- Create a new DateSelection table, this table will be placed on the slicer

DateSelection = DISTINCT ( 'Date'[Calendar WeekNumber] )

Step 2:- Create the measure

Last 4 Week Sales = 
VAR LastWeek = SELECTEDVALUE ( 'DateSelection'[Calendar WeekNumber] )
VAR FirstWeek = LastWeek - 3
VAR Result =
    CALCULATE (
        SUM ( 'Sales'[Sales] ),
        KEEPFILTERS (
            'Date'[Calendar WeekNumber] >= FirstWeek
                && 'Date'[Calendar WeekNumber] <= LastWeek
        )
    )
RETURN Result

Step 3:- Create the bar chart, by placing Date[Calendar WeekNumber] on the axis and [Last 4 Week Sales] on the values.

So, now for any week selected, the bar chart will show 4 bars, one bar for the selected week and 3 previous week.