I have the following calculations that give me a scrap %
![calc.PNG calc.PNG](https://community.qlik.com/t5/image/serverpage/image-id/24280iFAB2EF4DCA033DD3/image-size/large?v=v2&px=999)
And this heatmap shows that value over Date.autoCalendar.WeekYear by Platform
![heatmap.PNG heatmap.PNG](https://community.qlik.com/t5/image/serverpage/image-id/24281iF8EAE04CC9742705/image-size/large?v=v2&px=999)
I have received a request to change this instead to show the difference between the percentages on a weekly basis.
So for example, if last week our scrap % for a platform was 3.0% and this week it is 3.5%, the heatmap would display + 0.5% for the current week to show an increase. So 2019-44 in this case would show + 2.7%. I can't figure out how to calculate the change based on the previous week.