Re: [R] how to set debug breaks

From: Gavin Simpson <>
Date: Mon 30 Oct 2006 - 21:50:41 GMT

On Mon, 2006-10-30 at 10:37 -0800, waverley palo wrote:
> Hi,
> I am new in R and have some frustrations as how to set debug breaks during
> emacs R debug. I use debug () as where or which function to debug. But
> during the debug, e.g., I have a for loop at the beginning of the function
> code and want the code execution to jump through that for loop and set a
> break after that. How to do that? Is there a web site detailing the syntax
> of the debugging of R? Hopefully it would be similar to java or C syntax.

See ?debug, in particular the use of c to run to the end of the current context. So you can debug as before, but use c to run through the loop.

Alternatively, see ?browser, which drops you into the debugger wherever you insert the browser() command, e.g.:         

foo <- function(n = 10) {

	for(i in 1:n) {
	cat(paste("Doing something #", i, "\r"))
	cat("\nFinished loop\n")
	X <- runif(100)
	sumX <- sum(X)
	meanX <- mean(X)
	list(sum = sumX, mean = meanX)


Will start debugging foo() after the loop has finished.

You might also find Mark Bravington's debug package useful as it implements further functions for debugging in R


> Thanks.
> waverley

 Gavin Simpson                 [t] +44 (0)20 7679 0522
 ECRC & ENSIS, UCL Geography,  [f] +44 (0)20 7679 0565
 Pearson Building,             [e]
 Gower Street, London          [w]
 London, UK. WC1E 6BT.         [w]

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Received on Tue Oct 31 12:37:43 2006

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