

   AAccttuuaall AArrgguummeennttss

        substitute(arg, env=NULL)
        quote(arg, env=NULL)

   DDeessccrriippttiioonn::

        `substitute' returns the expression which was typed as
        the value of a formal argument.  `quote' is a synonym
        useful to lisp programmers.

        The typical use of this is to create informative labels
        for data sets and plots.  The following example shows a
        simple use of this facility.  It uses the functions
        `deparse' and `substitute' to create labels for a plot
        which are character string versions of the actual argu-
        ments to the function `myplot'.

   EExxaammpplleess::

        myplot <- function(x, y)
                plot(x, y, xlab=deparse(substitute(x)),
                        ylab=deparse(substitute(y)))

