## Actual Arguments

## Usage

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

## Description

`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 arguments to the function `myplot`.

## Examples

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

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