What is the recommended way to trap errors in R? My main need is to be able to trap an error and then skip a section of code if an error has occurred. In VB for Excel I used the ?On Error goto .....? construct to do this. Bernard Sent from my iPhone so please excuse the spelling!"
On 27/02/2019 3:55 p.m., Bernard Comcast wrote:> What is the recommended way to trap errors in R? My main need is to be able to trap an error and then skip a section of code if an error has occurred. In VB for Excel I used the ?On Error goto .....? construct to do this.The recommended way is to use tryCatch() around the expression you're evaluating. A simpler, less flexible alternative is try(). The Excel version sounds a bit more like try(). You'd use it like this: value <- try({ x <- 1 y <- someFunction(x) someOtherFunction(y) }) if (inherits(value, "try-error")) { cat ("something went wrong. There's information in value about what happened.") } else { cat ("value is fine, there was no error.") } Duncan Murdoch
Hello,
You can trap errors with ?try or ?tryCatch.
Example:
result <- vector(mode = "list", length = 5)
for(i in 1:5){
result[[i]] <- tryCatch(if(i == 3) stop("This is an error") else
2*i + 1,
error = function(e) e)
}
result
for(i in seq_along(result)) {
err <- inherits(result[[i]], "error")
print(err)
}
Hope this helps,
Rui Barradas
?s 20:55 de 27/02/2019, Bernard Comcast escreveu:> What is the recommended way to trap errors in R? My main need is to be able
to trap an error and then skip a section of code if an error has occurred. In VB
for Excel I used the ?On Error goto .....? construct to do this.
>
> Bernard
> Sent from my iPhone so please excuse the spelling!"
> ______________________________________________
> R-help at r-project.org mailing list -- To UNSUBSCRIBE and more, see
> https://stat.ethz.ch/mailman/listinfo/r-help
> PLEASE do read the posting guide
http://www.R-project.org/posting-guide.html
> and provide commented, minimal, self-contained, reproducible code.
>
Some use try blocks, like found in other languages. Put the code you want to try inside the block. https://www.robertknight.io/blog/try-blocks-in-r-for-error-handling/ contains a quick example. The example doesn?t raise exceptions or anything, it just contains it for you so the script keeps going. I like handling errors with if statements inside of try blocks. Robert> On Feb 27, 2019, at 2:55 PM, Bernard Comcast <mcgarvey.bernard at comcast.net> wrote: > > What is the recommended way to trap errors in R? My main need is to be able to trap an error and then skip a section of code if an error has occurred. In VB for Excel I used the ?On Error goto .....? construct to do this. > > Bernard > Sent from my iPhone so please excuse the spelling!" > ______________________________________________ > R-help at r-project.org mailing list -- To UNSUBSCRIBE and more, see > https://stat.ethz.ch/mailman/listinfo/r-help > PLEASE do read the posting guide http://www.R-project.org/posting-guide.html > and provide commented, minimal, self-contained, reproducible code.[[alternative HTML version deleted]]
Thanks Bernard Sent from my iPhone so please excuse the spelling!"> On Feb 27, 2019, at 4:05 PM, Duncan Murdoch <murdoch.duncan at gmail.com> wrote: > >> On 27/02/2019 3:55 p.m., Bernard Comcast wrote: >> What is the recommended way to trap errors in R? My main need is to be able to trap an error and then skip a section of code if an error has occurred. In VB for Excel I used the ?On Error goto .....? construct to do this. > > The recommended way is to use tryCatch() around the expression you're evaluating. A simpler, less flexible alternative is try(). The Excel version sounds a bit more like try(). You'd use it like this: > > value <- try({ x <- 1 > y <- someFunction(x) > someOtherFunction(y) > }) > if (inherits(value, "try-error")) { > cat ("something went wrong. There's information in value about what happened.") > } else { > cat ("value is fine, there was no error.") > } > > Duncan Murdoch
Thanks - the try() approach is exactly what I need. Lion Bernard McGarvey Director, Fort Myers Beach Lions Foundation, Inc. Retired (Lilly Engineering Fellow).> On February 27, 2019 at 4:39 PM Robert Knight <bobby.knight at gmail.com> wrote: > > Some use try blocks, like found in other languages. Put the code you want to try inside the block. > > https://www.robertknight.io/blog/try-blocks-in-r-for-error-handling/ contains a quick example. The example doesn?t raise exceptions or anything, it just contains it for you so the script keeps going. I like handling errors with if statements inside of try blocks. > > Robert > > > > On Feb 27, 2019, at 2:55 PM, Bernard Comcast < mcgarvey.bernard at comcast.net mailto:mcgarvey.bernard at comcast.net > wrote: > > > > > What is the recommended way to trap errors in R? My main need is to be able to trap an error and then skip a section of code if an error has occurred. In VB for Excel I used the ?On Error goto .....? construct to do this. > > > > Bernard > > Sent from my iPhone so please excuse the spelling!" > > ______________________________________________ > > R-help at r-project.org mailto:R-help at r-project.org mailing list -- To UNSUBSCRIBE and more, see > > https://stat.ethz.ch/mailman/listinfo/r-help > > PLEASE do read the posting guide http://www.R-project.org/posting-guide.html > > and provide commented, minimal, self-contained, reproducible code. > > > > >[[alternative HTML version deleted]]