

   OOppttiioonnss SSeettttiinnggss

        options(...)
        .Options

   AArrgguummeennttss::

        ...: 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 resize the window
             that R is running in.

     digits: controls the number of digits to print when print-
             ing numeric values. It is a suggestion only.

     editor: sets the default text editor, e.g., for `edit'.

    browser: default HTML browser used by `help.start()'.

   contrasts: the default `contrasts' used in model fitting
             such as with `aov' or `lm'.

   expressions: sets a limit on the number of nested expres-
             sions that will be evaluated.   This is especially
             important on the Macintosh since stack overflow is
             likely if this is set too high.

   na.action: the name of a function for treating missing val-
             ues (`NA''s) for certain situations.

      pager: the (standalone) program used for displaying ASCII
             files on R's console.  Defaults to
             `$RHOME/bin/pager'.

   papersize: the paper format used for graphics printing; cur-
             rently 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.

   DDeessccrriippttiioonn::

        `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.

   DDeettaaiillss::

        Invoking `options()' with no arguments returns a list
        with the current values of the options.  `.Options' is
        another way to access this list ``read only''.

        Accessing current options, usually will work with
        `.Options$width' (e.g.), rather than `options("width")'
        which is a list of length one.

   VVaalluuee::

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

   EExxaammpplleess::

        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')

