preplot.locfit can be called directly, although it is more usual
to call plot.locfit or predict.locfit.
The advantage of preplot.locfit is in S-Plus 5, where arithmetic
and transformations can be performed on the "preplot.locfit"
object. plot(preplot(fit)) is essentially synonymous with plot(fit).
## S3 method for class 'locfit':
preplot(object, newdata, where, tr=NULL, what="coef",
band="none", get.data=FALSE, f3d=FALSE, ...)locfit()."grid"
for the grid lfmarg(object); "data" for the original
data points and "fitp" for the direct fitting powhat="coef", works
with the fitted curve itself. Other choices include "nlx" for the
length of the weight diagram; "infl" for the influence function;
"ban"none". Other
choices include "global" for bands using a global variance estimate;
"local" for bands using a lTRUE, the original data is attached to the returned object, and
added to the plot.TRUE, sets a flag that forces ploting using the trellis style.
Not available in R."preplot.locfit", containing the predicted
values and additional information used to construct the plot.locfit, predict.locfit, plot.locfit.