R: Warning Messages

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)

### 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`.
`noBreaks.` | logical, indicating as far as possible the message should be output as a single line when `options(warn = 1)`.
`expr` | expression to evaluate.
`domain` | see `gettext`. If `NA`, messages will not be translated, see also the note in `stop`.

### 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.

### 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"))

[Package base version 3.1.2 Index]