How to convert a .Rnw to an R script

Question

I want to extract from an RNW all the chunks with R programming and put them in a separate file

I have a long rnw file and would find it tedious to do that manually.

Is there a function or a script to do that ?

Answer 1

You can perform some regex matching to retrieve all the code chunks as follows:

#read my Rnw file
l <- readLines("myRnw.Rnw")

#find starting and ending lines of my code chunks
startIdx <- which(grepl("^<<", l))
endIdx <- which(grepl("^@$", l))

#extract all code chunks and save to a file
writeLines(unlist(Map(function(st, ed) l[(st+1):(ed-1)], startIdx, endIdx)),
    "myRcode.R")