I\'ve found a way to use use bigrams instead of single tokens in a term-document matrix. The solution has been posed on stackoverflow here: findAssocs for multiple terms in
Seems there are problems using RWeka with parallel package. I found workaround solution here.
The most important point is not loading the RWeka package and use the namespace in a encapsulated function.
So your tokenizer should look like
BigramTokenizer <- function(x) {RWeka::NGramTokenizer(x, RWeka::Weka_control(min = 2, max = 2))}