Insert line breaks in long string -- word wrap

Question

Here is a function I wrote to break a long string into lines not longer than a given length

strBreakInLines <- function(s, breakAt=90, prepend="") {   words <- unlist(strsplit(s, " "))   if (length(words)<2) return(s)   wordLen <- unlist(Map(nchar, words))   lineLen <- wordLen[1]   res <- words[1]   lineBreak <- paste("\n", prepend, sep="")   for (i in 2:length(words)) {     lineLen <- lineLen+wordLen[i]     if (lineLen < breakAt)        res <- paste(res, words[i], sep=" ")     else {       res <- paste(res, words[i], sep=lineBreak)       lineLen <- 0     }   }   return(res) } 

It works for the problem I had; but I wonder if I can learn something here. Is there a shorter or more efficient solution, especially can I get rid of the for loop?

Answer 1

How about this:

gsub('(.{1,90})(\\s|$)', '\\1\n', s) 

It will break string "s" into lines with maximum 90 chars (excluding the line break character "\n", but including inter-word spaces), unless there is a word itself exceeding 90 chars, then that word itself will occupy a whole line.

By the way, your function seems broken --- you should replace

lineLen <- 0 

with

lineLen <- wordLen[i] 

Answer 2

For the sake of completeness, Karsten W.'s comment points at strwrap, which is the easiest function to remember:

strwrap("Lorem ipsum... you know the routine", width=10) 

and to match exactly the solution proposed in the question, the string has to be pasted afterwards:

paste(strwrap(s,90), collapse="\n") 

_{This post is deliberately made community wiki since the honor of finding the function isn't mine.}