\HeaderA{ggpath}{Grob function: path}{ggpath}
\keyword{hplot}{ggpath}
\begin{Description}\relax
Add a path (a line between points in the order that they appear in the dataset) to the plot
\end{Description}
\begin{Usage}
\begin{verbatim}ggpath(plot = .PLOT, aesthetics=list(), ..., data=plot$data)\end{verbatim}
\end{Usage}
\begin{Arguments}
\begin{ldescription}
\item[\code{plot}] the plot object to modify
\item[\code{aesthetics}] named list of aesthetic mappings, see details for more information
\item[\code{...}] other options, see details for more information
\item[\code{data}] data source, if not specified the plot default will be used
\end{ldescription}
\end{Arguments}
\begin{Details}\relax
Aesthetic mappings that this grob function understands:

\Itemize{
\item x: x position (required)
\item y: y position (required)
\item id: identifier variable used to break up into multiple paths
\item size: size of the line, in mm (see \code{\LinkA{scsize}{scsize}})
\item colour: line colour (see \code{\LinkA{sccolour}{sccolour}})
\item line\_type: line style/type (see \code{\LinkA{sclinetype}{sclinetype}})
}

These can be specified in the plot defaults (see \code{\LinkA{ggplot}{ggplot}}) or
in the \code{aesthetics} argument.  If you want to modify the position
of the points or any axis options, you will need to add a position scale to
the plot.  These functions start with \code{ps}, eg.
\code{\LinkA{pscontinuous}{pscontinuous}} or \code{\LinkA{pscategorical}{pscategorical}}

Other options:

\Itemize{
\item none
}
\end{Details}
\begin{Author}\relax
Hadley Wickham <h.wickham@gmail.com>
\end{Author}
\begin{Examples}
\begin{ExampleCode}myear <- do.call(rbind, by(movies, movies$year, function(df) data.frame(year=df$year[1], mean.length = mean(df$length), mean.rating=mean(df$rating))))
p <- ggplot(myear, aesthetics=list(x=mean.length, y=mean.rating))
ggpath(p)
ggpath(p, list(size=year))
ggpath(p, list(colour=year))
ggpath(scsize(p, c(0.5,1)), list(size=year))
ggpath(scsize(p, c(0.5,1)), list(size=year))
p <- ggplot(mtcars, aesthetics=list(x=drat, y=wt))
ggpath(p)
ggpath(p, list(id=cyl))\end{ExampleCode}
\end{Examples}

