Variance based on Category and Period

Hello,
I have a table which look like below:

I want to do the variance among categories based on Period. For example in slicer of period if I choose Period 1 and Period 2 the variance should be shown against the category as shown in the picture below:

Similarly If I choose the slicer 1 and 3 the ourcome would be the variance between both the periods as below:

I just want the variance to filter automatically between the two selection made in the slicer. 
Your help would be highly appreciated.
Thank you