My question is a follow-up to Grouping Over All Possible Combinations of Several Variables With dplyr. In above thread, the poster was looking at grouping by all combinations of grouping variables using dplyr. However, this solution doesn't work for my dataset because of memory and size limitations. Can someone please help me with data.table version of it?
Input data and output format are going to be the same as that of the question in above post and Gregor's answer. So, for sake of brevity, I am not posting it again.
I tried this myself using data.table, but I don't know how to nest data.table operations inside do.call(). I searched for this, and found do.call to build and execute data.table commands, but Matt's post is beyond my comprehension.
I'd appreciate any help.
