Performance comparison of deparsing character vectors

deparse_vector.R

# Version 1
deparse_vector1 <- function(x) {
  stopifnot(is.character(x))
  vapply(x, deparse, character(1), USE.NAMES=FALSE)
}

# Version 2
deparse_vector2 <- function(x) {
  stopifnot(is.character(x))
  if(!length(x)) return(x)
  x <- gsub("\\", "\\\\", x, fixed=TRUE)
  x <- gsub("\"", "\\\"", x, fixed=TRUE)
  x <- gsub("\n", "\\n", x, fixed=TRUE)
  x <- gsub("\r", "\\r", x, fixed=TRUE)
  x <- gsub("\t", "\\t", x, fixed=TRUE)
  x <- gsub("\b", "\\b", x, fixed=TRUE)
  x <- gsub("\f", "\\f", x, fixed=TRUE)
  paste0("\"", x, "\"")
}

# Create vector with random trings
mychars <- c(letters, " ", '"', "\\", "\t", "\n", "\r", "'", "/", "#", "$");
createstring <- function(length){
  paste(mychars[ceiling(runif(length, 0, length(mychars)))], collapse="")
}
strings <- vapply(rep(1000, 10000), createstring, character(1), USE.NAMES=FALSE)

# Test performance
system.time(out1 <- deparse_vector1(strings))
system.time(out2 <- deparse_vector2(strings))

# Verify that escape was correct
orig1 <- vapply(out1, function(x){parse(text=x)[[1]]}, character(1), USE.NAMES=FALSE)
orig2 <- vapply(out2, function(x){parse(text=x)[[1]]}, character(1), USE.NAMES=FALSE)
identical(strings, orig1)
identical(strings, orig2)