Hi - I am trying to create a graph where it displays the number of items selected by the user. These items are marked through booleans. Is there a way where I can count how many items are selected per category using the booleans?
I am afraid that you feel some dissatisfaction with doubling cell counts to get one mere aggregation number. But if I were you, I would do this. A tricky way is sometimes not well understood by others.
If you specifically want a category count you can create the line item as @anirudh and @Amaya suggest and also create a system module that allows you to filter on categories so you can get the total count for categories.
If your use case only requires you to know if ANY Booleans are checked you can use this little trick to to refer to the Year value of the Booleans. It won't give you a count but it will give you a TRUE / FALSE on the category.