xyVector               package:splines               R Documentation

Construct an xyVector Object

Description:

     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 'y' component
     only.

     The result of functions such as 'predict.spline' is returned as an
     'xyVector' object so the x-values used to generate the y-positions
     are retained, say for purposes of generating plots.

Usage:

     xyVector(x, y)

Arguments:

       x: a numeric vector

       y: a numeric vector of the same length as 'x'

Value:

     An object of class 'xyVector' with components 

       x: a numeric vector

       y: a numeric vector of the same length as 'x'

Author(s):

     Douglas Bates and Bill Venables

Examples:

     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

