| warning {base} | R Documentation |
Warning Messages
Description
Generates a warning message that corresponds to its argument(s) and (optionally) the expression or function from which it was called.
Usage
warning(..., call. = TRUE, immediate. = FALSE, noBreaks. = FALSE,
domain = NULL)
suppressWarnings(expr, classes = "warning")
Arguments
... |
either zero or more objects which can be coerced to character (and which are pasted together with no separator) or a single condition object. |
call. |
logical, indicating if the call should become part of the warning message. |
immediate. |
logical, indicating if the warning should be output
immediately, even if |
noBreaks. |
logical, indicating as far as possible the message should
be output as a single line when |
expr |
expression to evaluate. |
domain |
see |
classes |
character, indicating which classes of warnings should be suppressed. |
Details
The result depends on the value of
options("warn") and on handlers established in the
executing code.
If a condition object is supplied it should be the only
argument, and further arguments will be ignored, with a message.
options(warn = 1) can be used to request an immediate
report.
warning signals a warning condition by (effectively) calling
signalCondition. If there are no handlers or if all handlers
return, then the value of warn = getOption("warn") is
used to determine the appropriate action. If warn is negative
warnings are ignored; if it is zero they are stored and printed after
the top–level function has completed; if it is one they are printed
as they occur and if it is 2 (or larger) warnings are turned into
errors. Calling warning(immediate. = TRUE) turns warn <=
0 into warn = 1 for this call only.
If warn is zero (the default), a read-only variable
last.warning is created. It contains the warnings which can be
printed via a call to warnings.
Warnings will be truncated to getOption("warning.length")
characters, default 1000, indicated by [... truncated].
While the warning is being processed, a muffleWarning restart
is available. If this restart is invoked with invokeRestart,
then warning returns immediately.
An attempt is made to coerce other types of inputs to warning
to character vectors.
suppressWarnings evaluates its expression in a context that
ignores all warnings.
Value
The warning message as character string, invisibly.
References
Becker, R. A., Chambers, J. M. and Wilks, A. R. (1988) The New S Language. Wadsworth & Brooks/Cole.
See Also
stop for fatal errors,
message for diagnostic messages,
warnings,
and options with argument warn=.
gettext for the mechanisms for the automated translation
of messages.
Examples
testit <- function() warning("testit")
testit() ## shows call
testit <- function() warning("problem in testit", call. = FALSE)
testit() ## no call
suppressWarnings(warning("testit"))