[R] need help on GAM

[Liu Song]

Get some question about the function "gam".
Suppose I have a semiparametric model,
Y~x1+x2+s(z1).
Using "gam", how could I get the estimates for the parametric part and 
nonparametric part respectively?

And another question: we could find the coefficients for both 
parametric term and nonparametric term, what do these coefficients
for the nonparametric term stand for, the coefficients for the base 
functions?
 
Thank you!

Song
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Song Liu
School of Statistics
313 FordH
224 Church St. SE
Minneapolis,MN 55455