[R] mgcv gam predict problem

[Vito Muggeo (UniPa)]

dear Philip,
I am not able to solve your problem, however the error message you get 
does not depends on mgcv::gam, therefore gam(,..outer.ok=TRUE) or 
predict.gam(,outer.ok=TRUE) do not make sense.

The error message comes from the function splines::splineDesign which is 
called when the option bs="ps" is used.

I think the error depends on the fact that you want to "predict" a value 
outside the observed range of the covariate. When using P-splines the 
predictions outside the range follow a given polynomial..

hope this helps
vito




Il 28/03/2011 7.10, Philip Gautier ha scritto:
> Hello
>
> I'm using function gam from package mgcv to fit splines.  When I try
> to make a prediction slightly beyond the original 'x' range, I get
> this error:
>
>> A = runif(50,1,149)
>> B = sqrt(A) + rnorm(50)
>> range(A)
> [1]   3.289136 145.342961
>>
>>
>> fit1 = gam(B ~ s(A, bs="ps"), outer.ok=TRUE)
>> predict(fit1, newdata=data.frame(A=149.9), outer.ok=TRUE)
> Error in splineDesign(knots, x, ord, derivs, outer.ok = outer.ok) :
>    the 'x' data must be in the range 3.14708 to 145.485 unless you set
> 'outer.ok = TRUE'
>>
>
> I've inserted the argument 'outer.ok=TRUE' as you can see, but it
> hasn't helped.  How can I obtain this prediction?
>
> Thanks,
> Philip Gautier
> Dept. of Mathematics and Statistics
> American University, Washington, DC
>
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-- 
====================================
Vito M.R. Muggeo
Dip.to Sc Statist e Matem `Vianelli'
Università di Palermo
viale delle Scienze, edificio 13
90128 Palermo - ITALY
tel: 091 23895240
fax: 091 485726/485612
http://dssm.unipa.it/vmuggeo