\Header{plot.formula}{Formula Notation for Scatterplots}
\keyword{hplot}{plot.formula}
\begin{Usage}
\begin{verbatim}
plot.formula(formula, data = NULL, subset, na.action, ..., ask = TRUE)
plot(y ~ x, ...)
\end{verbatim}
\end{Usage}
\begin{Arguments}
\begin{ldescription}
\item[\texttt{formula}] a \texttt{\Link{formula}}, such as \texttt{y $\,\tilde{\,}$ x}.
\item[\texttt{data}] a data.frame (or list) from which the variables in
\texttt{formula} should be taken.
\item[\texttt{subset}] an optional vector specifying a subset of observations
to be used in the fitting process.
\item[\texttt{na.action}] a function which indicates what should happen
when the data contain \texttt{NA}s.  The default action (\texttt{na.omit})
is to omit any incomplete observations.
The alternative action \texttt{na.fail} causes \texttt{plot} to
print an error message and terminate if there are any incomplete
observations.
\item[\texttt{...}] graphical parameters may also be passed as arguments, see
\texttt{\Link{par}}. These can include \texttt{ylab}, which if not
supplied is set by \texttt{plot.formula}.
\item[\texttt{ask}] logical, see \texttt{\Link{par}}.
\end{ldescription}
\end{Arguments}
\begin{Value}
This function is invoked for its side effect of drawing a scatter plot
in the active graphics window.\end{Value}
\begin{SeeAlso}
\texttt{\Link{plot.default}}, \texttt{\Link{plot.factor}}.\end{SeeAlso}
\begin{Examples}
\begin{ExampleCode}
data(swiss)
op <- par(mfrow=c(2,1))
plot(Fertility ~ Education, data = swiss)
plot(Fertility ~ Education, data = swiss, subset = Education < 20)
par(op)
\end{ExampleCode}
\end{Examples}

