warning                 package: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, domain = NULL)
     suppressWarnings(expr)

Arguments:

     ...: 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 call should be output
          immediately, even if 'getOption("warn") <= 0'.

    expr: expression to evaluate.

  domain: see 'gettext'. If 'NA', messages will not be translated.

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.

     '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.

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"))

