\HeaderA{xyVector}{Construct an xyVector Object}{xyVector}
\keyword{models}{xyVector}
\begin{Description}\relax
Create an object to represent a set of x-y pairs.  The resulting
object can be treated as a matrix or as a data frame or as a vector.
When treated as a vector it reduces to the \code{y} component only.

The result of functions such as \code{predict.spline} is returned as
an \code{xyVector} object so the x-values used to generate the
y-positions are retained, say for purposes of generating plots.
\end{Description}
\begin{Usage}
\begin{verbatim}
xyVector(x, y)
\end{verbatim}
\end{Usage}
\begin{Arguments}
\begin{ldescription}
\item[\code{x}] a numeric vector
\item[\code{y}] a numeric vector of the same length as \code{x}
\end{ldescription}
\end{Arguments}
\begin{Value}
An object of class \code{xyVector} with components
\begin{ldescription}
\item[\code{x}] a numeric vector
\item[\code{y}] a numeric vector of the same length as \code{x}
\end{ldescription}
\end{Value}
\begin{Author}\relax
Douglas Bates and Bill Venables
\end{Author}
\begin{Examples}
\begin{ExampleCode}
require(stats); require(graphics)
ispl <- interpSpline( weight ~ height, women )
weights <- predict( ispl, seq( 55, 75, length.out = 51 ))
class( weights )
plot( weights, type = "l", xlab = "height", ylab = "weight" )
points( women$height, women$weight )
weights
\end{ExampleCode}
\end{Examples}

