[R] obtaining coefficients from a pspline fit
nirmalg at psu.edu
Sat Mar 29 02:13:44 CET 2003
Hi.. I'm relatively new to both nonparametric modeling and R.. I'm trying to fit
a regression spline or a piecewise polynomial using R and have teh following
1. How do I fit a regression spline/piecewise polynomial to the data for some
specified degree of the polynomial?
2. How do I obtain the coefficients of the model?
I tried the following (based on an example in the help):
> plot(speed, dist, main = "data(cars) & smoothing splines")
> cars.spl <- sm.spline(speed, dist)
smooth.Pspline(x = ux, y = tmp[, 1], w = tmp[, 2], method = method)
Smoothing Parameter (Spar): 366.8429
Equivalent Degrees of Freedom (Df): 2.428851
GCV Criterion: 29.54554
CV Criterion: 39.18787
As seen above, it doesn't give me the coefficients though it seems to have
fitted a piecewise linear model.. I just get "NULL".. is there some other
function that will do this?
Please cc me on the reply as I'm not subscribed to the list yet..
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