Generating a very large matrix of string combinations using combn() and bigmemory package

Question

I have a vector x of 1,344 unique strings. I want to generate a matrix that gives me all possible groups of three values, regardless of order, and export that to a csv.

Answer 1

At a first approximation, every algorithm trades off storage for speed.

You have hit a boundary trying to preallocate your fully enumerated combination matrix. So maybe you should try not to preallocate this matrix but to try, say,

1. If you think you need the combinations, calculate them somewhere else and store them in a simple db (or, heck, flat file) and look them up -- 9 gb saved

2. Take advantage of open source, read the code to combn() and modify it into a client-server thingy: given a call with index number N, it will loop and return the Nth entry. Not efficient, but possibly more easily feasible.