Re: [Rd] suppress *specific* warnings?

From: Ben Bolker <bbolker_at_gmail.com>
Date: Sun, 21 Oct 2012 21:25:45 -0400

On 12-10-21 09:08 PM, Martin Morgan wrote:
> On 10/21/2012 12:28 PM, Ben Bolker wrote:

>>
>>    Not desperately important, but nice to have and possibly of use to
>> others, is the ability to suppress specific warnings rather than
>> suppressing warnings indiscriminately.  I often know of a specific
>> warning that I want to ignore (because I know that's it's a false
>> positive/ignorable), but the current design of suppressWarnings() forces
>> me to ignore *any* warnings coming from the expression.
>>
>>    I started to write a new version that would check and, if supplied
>> with a regular expression, would only block matching warnings and
>> otherwise would produce the warnings as usual, but I don't quite know
>> enough about what I'm doing: see ??? in expression below.
>>
>>    Can anyone help, or suggest pointers to relevant
>> examples/documentation (I've looked at demo(error.catching), which isn't
>> helping me ... ?)
>>
>> suppressWarnings2 <- function(expr,regex=NULL) {
>>      opts <- options(warn = -1)
>>      on.exit(options(opts))

>
> I'm not really sure what the options(warn=-1) is doing there, maybe its
> for efficiency to avoid generating a warning message (as distinct from
> signalling a warning).

  As may have been obvious, I was copying suppressWarnings() verbatim -- so I guess you'd have to ask R-core for the reasoning there ...

> I think you're after something like
>
> suppressWarnings2 <-
> function(expr, regex=character())
> {
> withCallingHandlers(expr, warning=function(w) {
> if (length(regex) == 1 && length(grep(regex,
> conditionMessage(w)))) {
> invokeRestart("muffleWarning")
> }
> })
> }
>
> If the restart isn't invoked, then the next handler is called and the
> warning is handled as normal. So with
>
> f <- function() {
> warning("oops")
> 2
> }
>
> there is
>

>> suppressWarnings2(f())

> [1] 2
> Warning message:
> In f() : oops

>> suppressWarnings2(f(), "oops")
> [1] 2

  Great, thank you!

>
> For your own code I think a better strategy is to create a sub-class of
> warnings that can be handled differently
>
> mywarn <-
> function(..., call.=TRUE, immediate.=FALSE, domain=NULL)
> {
> msg <- .makeMessage(..., domain=domain, appendLF=FALSE)
> call <- NULL
> if (call.)
> call <- sys.call(1L)
> class <- c("silencable", "simpleWarning", "warning", "condition")
> cond <- structure(list(message=msg, call=call), class=class)
> warning(cond)
> }
>
> suppressWarnings3 <-
> function(expr)
> {
> withCallingHandlers(expr, silencable=function(w) {
> invokeRestart("muffleWarning")
> })
> }
>
> then with
>
> g <- function() {
> mywarn("oops")
> 3
> }
>

>> suppressWarnings3(f())

> [1] 2
> Warning message:
> In f() : oops
>> g()

> [1] 3
> Warning message:
> In g() : oops
>> suppressWarnings3(g())

> [1] 3
>
>>      withCallingHandlers(expr, warning = function(w) {
>>          ## browser()
>>          if (is.null(regex) || grepl(w[["message"]],regex)) {
>>              invokeRestart("muffleWarning")
>>          } else {
>>              ## ? what do I here to get the warning issued?
>>              ## browser()
>>              ## computeRestarts() shows "browser",
>>              ##    "muffleWarning", and "abort" ...
>>              options(opts)
>>              warning(w$message)
>>              ## how can I get back from here to the calling point
>>              ##   *without* muffling warnings ... ?
>>          }
>>      })
>> }
>>
>> suppressWarnings2(sqrt(-1))
>> suppressWarnings2(sqrt(-1),"abc")
>>
>>    It seems to me I'd like to have a restart option that just returns to
>> the point where the warning was caught, *without* muffling warnings ...
>> ?  But I don't quite understand how to set one up ...
>>
>>    Ben Bolker
>>
>> ______________________________________________
>> R-devel_at_r-project.org mailing list
>> https://stat.ethz.ch/mailman/listinfo/r-devel
>>

>

>

R-devel_at_r-project.org mailing list
https://stat.ethz.ch/mailman/listinfo/r-devel Received on Mon 22 Oct 2012 - 01:28:15 GMT

This quarter's messages: by month, or sorted: [ by date ] [ by thread ] [ by subject ] [ by author ]

All messages

Archive maintained by Robert King, hosted by the discipline of statistics at the University of Newcastle, Australia.
Archive generated by hypermail 2.2.0, at Mon 22 Oct 2012 - 17:10:50 GMT.

Mailing list information is available at https://stat.ethz.ch/mailman/listinfo/r-devel. Please read the posting guide before posting to the list.

list of date sections of archive