[R] warnings details

Duncan Murdoch murdoch at stats.uwo.ca
Sat Oct 24 12:28:15 CEST 2009

Erich Neuwirth wrote:
> I am running R as an invisible subprocess in another program (RExcel).
> Using try I can catch errors and print the errors produced by an R
> statement.
> Is there a way to know if running a statement caused a warning message?
> last.warning gives me the last warning, but I do not have any indication
> what the statement was that caused the message.
> I can of course store last warning before I run
> a statement and then compare last.warning with this stored message
> to see if it has changed, but that is
> a) clumsy
> b) still does not cover situations when I get the same warning
> as the last one by coincidence.

You could clear the old message by issuing your own warning, e.g.

warning("Cleared warnings in RExcel")
save.warning <- last.warning
 ...  do something ...
if (!identical(last.warning, save.warning))

Working at a lower level, the R_WriteConsoleEx function tells a GUI 
whether it is writing a regular message or a warning/error, so you could 
keep track of that if you're working at that level.

Duncan Murdoch

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