sapply with progress text (percent complete)

pbsapply.R

pbsapply <- function(x, fun, pass_to, ...) {
  if(!missing('pass_to')) {
    call <- sprintf('fun(%s=x[[i]], ...)', pass_to)
  } else {
    call <- 'fun(x[[1]], ...) '
  }
  sapply(seq_along(x), function(i) {
    cat(sprintf('\r%.02f%%', i/length(x)*100))
    eval(parse(text=call))  
  })
}

pbsapply(runif(5), Sys.sleep, pass_to='time')