options {base}R Documentation

Options Settings

Description

options allows the user to set and examine a variety of global ``options'' which affect the way in which R computes and displays its results.

Usage

options(...)
getOption(x)
.Options

Arguments

... any options can be defined, using name = value. However, only the ones below are used in ``base R''.

Further, options('name') == options()['name'], see the example.

prompt a string, used for R's prompt; should usually end in a blank (" ").
continue a string setting the prompt used for lines which continue over one line.
width controls the number of characters on a line. You may want to change this if you re-size the window that R is running in.
digits controls the number of digits to print when printing numeric values. It is a suggestion only.
editor sets the default text editor, e.g., for edit. Set from the environment variable VISUAL on UNIX.
pager the (stand-alone) program used for displaying ASCII files on R's console. Defaults to `$R_HOME/bin/pager' on UNIX.
browser default HTML browser used by help.start() on UNIX.
mailer default mailer used by bug.report(). can be "none".
contrasts the default contrasts used in model fitting such as with aov or lm. A character vector of length two, the first giving the function to be used with unordered factors and the second the function to be used with ordered factors.
expressions sets a limit on the number of nested expressions that will be evaluated. This is especially important on the Macintosh since stack overflow is likely if this is set too high.
keep.source When TRUE, the default, the source code for functions loaded by is stored in their "source" attribute, allowing comments to be kept in the right places. This does not apply to functions loaded by library.
na.action the name of a function for treating missing values (NA's) for certain situations.
papersize the paper format used for graphics printing; currently read-only, set by environment variable R_PAPERSIZE, or in `config.site'.
printcmd the command used for graphics printing; currently read-only, set by environment variable R_PRINTCMD, or in `config.site'.
show.signif.stars, show.coef.Pvalues logical, affecting P value printing, see print.coefmat.
ts.eps the relative tolerance for certain time series (ts) computations.
error an expression governing the handling of non-catastrophic errors such as those generated by stop as well as by signals and internally detected errors. The default expression is NULL: see stop for the behaviour in that case. The function dump.frames provides one alternative that allows post-mortem debugging.
show.error.messages a logical. Should error messages be printed? Intended for use with try or a user-installed error handler.
warn sets the handling of warning messages. If warn is negative all warnings are ignored. If warn is zero (the default) warnings are stored until the top–level function returns. If fewer than 10 warnings were signalled they will be printed otherwise a message saying how many (max 50) were signalled. A top–level variable called last.warning is created and can be viewed through the function warnings. If warn is one, warnings are printed as they occur. If warn is two or larger all warnings are turned into errors.
echo logical. Only used in non-interactive mode, when it controls whether input is echoed. Command-line options --quiet and --slave set this initially to FALSE.
verbose logical. Should R report extra information on progress? Set to TRUE by the command-line option --verbose.
device a character string giving the default device for that session.
CRAN The URL of the preferred CRAN node for use by update.packages. Defaults to http://cran.r-project.org.
unzip the command used unzipping help files. Defaults to "internal" when the internal unzip DLL is used.
x a character string holding one of the above option names.

Details

Invoking options() with no arguments returns a list with the current values of the options. To access the value of a single option, one should use getOption("width"), e.g., rather than options("width") which is a list of length one.

The default settings of some of these options are
prompt "> " continue "+ "
width 80 digits 7
expressions 500 keep.source TRUE
show.signif.stars TRUE show.coef.Pvalues TRUE
na.action na.omit ts.eps 1e-5
error NULL warn 0
echo TRUE verbose FALSE
Others are set from environment variables or are platform-dependent.

Value

A list (in any case) with the previous values of the options changed, or all options when no arguments were given.

Examples

options() # printing all current options
op <- options(); str(op) # nicer printing

# .Options is the same:
all(sapply(1:length(op), function(i) all(.Options[[i]] == op[[i]])))

options('width')[[1]] == options()$width # the latter needs more memory
options(digits=20)
pi

# set the editor, and save previous value
old.o <- options(editor="nedit")
old.o

options(op)     # reset (all) initial options
options('digits')

## set contrast handling to be like S
options(contrasts=c("contr.helmert", "contr.poly"))

## on error, terminate the R session with error status 66
options(error=quote(q("no", status=66, runLast=FALSE)))
stop("test it")
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