plot.locfit() function is implemented, roughly, as
a call to preplot.locfit(), followed by a call to
plot.locfitpred(). For most users, there will be little
need to call plot.locfitpred() directly.plot(object, ...)"locfitpred" object, produced by
preplot.locfit().plot.locfit.1d, plot.locfit.2d or
plot.locfit.3d as appropriate.locfit, plot.locfit,
preplot.locfit, plot.locfit.1d,
plot.locfit.2d, plot.locfit.3d.