Slice a string at consecutive indices with R / Rcpp?

Question

I want to write a function that slices a \'string\' into a vector, sequentially, at a given index. I have a fairly adequate R solution for it; however, I figure that writing

Answer 1

This one-liner using strapplyc from the gsubfn package is fast enough that rcpp may not be needed. Here we apply it to the entire text of James Joyce's Ulysses which only takes a few seconds:

library(gsubfn)
joyce <- readLines("http://www.gutenberg.org/files/4300/4300-8.txt") 
joycec <- paste(joyce, collapse = " ") # all in one string 
n <- 2
system.time(s <- strapplyc(joycec, paste(rep(".", n), collapse = ""))[[1]])