Compare YoY by weeknumber

Hi,

I've searched online but cannot find an answer.

We measure sales by week. In table 1 I simply have date, sales. In table 2 date and week number. I created a YoY calc by date with no issue using SAMEPERIODLASTYEAR, all worked fine. But of course I am now comparing a Monday with a Sunday or similar. When I remove the date from the visual I get an error as it expects a date and week number is not a date.

There does not seem to be a way to do a YoY for week number.

Thanks,

Matt