[R] Find the prediction or the fitted values for an lm model
Achim.Zeileis at uibk.ac.at
Thu Nov 28 09:17:45 CET 2013
On Thu, 28 Nov 2013, jpm miao wrote:
> I would like to fit my data with a 4th order polynomial. Now I have only
> 5 data point, I should have a polynomial that exactly pass the five point
> Then I would like to compute the "fitted" or "predict" value with a
> relatively large x dataset. How can I do it?
> BTW, I thought the model "prodfn" should pass by (0,0), but I just
> wonder why the const is unequal to zero
> prodfn<-lm(y1 ~ poly(x1, 4))
> temp<-predict(prodfn,data.frame(x=x)) # This line does not work..
You need to call the variable x1 because that is the name you used in the
plot(x, predict(prodfn,data.frame(x1=x)), type = "l")
> lm(formula = y1 ~ poly(x1, 4))
> (Intercept) poly(x1, 4)1 poly(x1, 4)2 poly(x1, 4)3 poly(x1, 4)4
> 4.000e+00 6.517e+00 -4.918e-16 -2.744e+00 -8.882e-16
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