On 2010-12-06, at 01:07 , David Winsemius wrote:
>
> On Dec 5, 2010, at 3:13 PM, Marius Hofert wrote:
>
>> Dear expeRts,
>>
>> I am struggling with warning/error handling.
>>
>> I would like to call a function which can produce either
>> a) normal output
>> b) a warning
>> c) an error
>>
>> Since the function is called several (thousand) times in a loop, I would like
>> to proceed "quietly" and collect the warnings and errors [to deal with them
>> at a
>> later point].
>
> I do not see the function warnings() being used below:
>
> ?warnings
>
> It delivers the stored warnings with different default behavior for
> interactive and non-interactive sessions.
>>
>> I have seen constructs with tryCatch (which can deal with errors) and with
>> withCallingHandlers (which can deal with warnings), but I cannot figure out
>> how
>> to catch *both* warnings and errors. Below is a minimal example of the
>> function
>> that is called several times in a large loop. The function should catch
>> warnings
>> and errors; the former work fine, but with the latter I do not know how to
>> proceed.
>>
>
>
> Made some changes in you code but don't know if it is what you were hoping
> for:
>
> f <- function(x){
> ## warnings
> w.list <- NULL # init warning
> w.handler <- function(w){ # warning handler
> warn <- simpleWarning(w$message, w$call) # build warning
> # first change here
> w.list <<- c(w.list, paste(warnings(), collapse = " ")) # save warning
> invokeRestart("muffleWarning")
> }
> ## errors
> e.list <- NULL # init errors # not sure this is good idea
> e.handler <- function(e){ # error handler
> err <- c(e.list, e$message, e$call) # save error
> return( err)
> }
> ## execute command
> # wrapped cal in try()
> res <- withCallingHandlers(try(log(x)), warning = w.handler, error =
> e.handler)
> ## return result with warnings and errors
> list(result = res, warning = w.list, error = e.list)
> }
>
Dear David,
many thanks for your help.
If I call your code with f(-1) and f("a"), I obtain:
> f(-1)
$result
[1] NaN
$warning
[1] ""
$error
NULL
=> The problem is that the warning is not given.
> f("a")
Error in log(x) : Non-numeric argument to mathematical function
$result
[1] "Error in log(x) : Non-numeric argument to mathematical function\n"
attr(,"class")
[1] "try-error"
$warning
NULL
$error
NULL
=> The problem is that the error message is printed to the R console instead of
suppressed (setting silent = TRUE didn't help either). Further, the $error
component is empty (the error message should appear there -- if possible)
Do you know a solution?
Cheers,
Marius
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