ksmooth                package:stats                R Documentation

Kernel Regression Smoother

Description:

     The Nadaraya-Watson kernel regression estimate.

Usage:

     ksmooth(x, y, kernel = c("box", "normal"), bandwidth = 0.5,
             range.x = range(x),
             n.points = max(100, length(x)), x.points)

Arguments:

       x: input x values

       y: input y values

  kernel: the kernel to be used.

bandwidth: the bandwidth. The kernels are scaled so that their
          quartiles (viewed as probability densities) are at +/-
          '0.25*bandwidth'.

 range.x: the range of points to be covered in the output.

n.points: the number of points at which to evaluate the fit.

x.points: points at which to evaluate the smoothed fit. If missing,
          'n.points' are chosen uniformly to cover 'range.x'.

Value:

     A list with components 

       x: values at which the smoothed fit is evaluated. Guaranteed to
          be in increasing order.

       y: fitted values corresponding to 'x'.

Note:

     This function is implemented purely for compatibility with S,
     although it is nowhere near as slow as the S function. Better
     kernel smoothers are available in other packages.

Examples:

     require(graphics)

     with(cars, {
         plot(speed, dist)
         lines(ksmooth(speed, dist, "normal", bandwidth=2), col=2)
         lines(ksmooth(speed, dist, "normal", bandwidth=5), col=3)
     })

