Problems with tryCatch()

Question

I'm trying to built a script in R that looks like this:

randomlist <- list(x=ran1, y=ran2) #{x,y}
contour <- Conte(c(round(randomlist$x),round(randomlist$y)),img@grey)
#if Conte function returns me an error, then get new randomlist values
#Do until it doesn't returns an error

The functions returns the coordinates of a contour image if the random {x,y} are inside a region of the image. I know that maybe this is kind of dumb and not so clear question but I'm not good at R and the error handling is a mess for me. I tried with tryCatch() but I can't figure out how to apply it. Thank you very much!

Answer 1

Reproducible code would help. I usually handle these sorts of problems with try eg:

temp <- function(N) {
  if (N < 0) stop("Error")
  return(N)
}

out <- 0 
n <- 0 
out <- try(temp(rnorm(1)))
while(class(out) == "try-error") {
 n <- n + 1
 print(n) 
 out <- try(temp(rnorm(1))) 
}  
out