Function to get a code block from a StackOverflow question.

gistfile1.r

##' Get code block from a SO question
##' 
##' @param id question id 
##' @param index index of the code block to return (one number only)
##' @param cat.output cat the content of the code blocks
##' @import XML
##' @export
get.so <- function (id, index=NULL, cat.output=FALSE) { 
  doc <- htmlParse(paste("http://stackoverflow.com/questions/",id,sep=""))
  pre.index <- ifelse(is.null(index), "", paste("[",as.character(index),"]",sep=""))
  xpath <- paste("//div[@id=\"question\"]//div[@class=\"post-text\"]//pre",pre.index,"/code",sep="")
  code <- getNodeSet(doc, xpath)
  code <- lapply(code, getChildrenStrings)
  if (cat.output) return(invisible(lapply(code, cat)))
  if (length(code)==1) return(unlist(code))
  code
}