R: ngram dan frekuensi-nya

library(tau) 
library(data.table)
# given a string vector and size of ngrams this function returns     word ngrams with corresponding frequencies

createNgram <-function(stringVector, ngramSize){
  ngram <- data.table()
  ng <- textcnt(stringVector, method = "string", n=ngramSize, tolower = FALSE)
  if(ngramSize==1){
    ngram <- data.table(w1 = names(ng), freq = unclass(ng), length=nchar(names(ng)))  
  }
  else {
    ngram <- data.table(w1w2 = names(ng), freq = unclass(ng), length=nchar(names(ng)))
  }
  return(ngram)
}

text <- "This is my little R text example and I want to count the frequency of some pattern (and - is - my - of). This is my little R text example and I want to count the frequency of some patter."
res <- createNgram(text, 2)
res