[R] boot.stepAIC fails with computed formula

[Bert Gunter]

Failed?  What was the error message?

Cheers,

Bert


Bert Gunter

"The trouble with having an open mind is that people keep coming along
and sticking things into it."
-- Opus (aka Berkeley Breathed in his "Bloom County" comic strip )


On Tue, Aug 22, 2017 at 8:17 AM, Stephen O'hagan
<SOhagan at manchester.ac.uk> wrote:
> I'm trying to use boot.stepAIC for feature selection; I need to be able to specify the name of the dependent variable programmatically, but this appear to fail:
>
> In R-Studio with MS R Open 3.4:
>
> library(bootStepAIC)
>
> #Fake data
> n<-200
>
> x1 <- runif(n, -3, 3)
> x2 <- runif(n, -3, 3)
> x3 <- runif(n, -3, 3)
> x4 <- runif(n, -3, 3)
> x5 <- runif(n, -3, 3)
> x6 <- runif(n, -3, 3)
> x7 <- runif(n, -3, 3)
> x8 <- runif(n, -3, 3)
> y1 <- 42+x3 + 2*x6 + 3*x8 + runif(n, -0.5, 0.5)
>
> dat <- data.frame(x1,x2,x3,x4,x5,x6,x7,x8,y1)
> #the real data won't have these names...
>
> cn <- names(dat)
> trg <- "y1"
> xvars <- cn[cn!=trg]
>
> frm1<-as.formula(paste(trg,"~1"))
> frm2<-as.formula(paste(trg,"~ 1 + ",paste(xvars,collapse = "+")))
>
> strt=lm(y1~1,dat) # boot.stepAIC Works fine
>
> #strt=do.call("lm",list(frm1,data=dat)) ## boot.stepAIC FAILS ##
>
> #strt=lm(frm1,dat) ## boot.stepAIC FAILS ##
>
> limit<-5
>
>
> stp=stepAIC(strt,direction='forward',steps=limit,
>             scope=list(lower=frm1,upper=frm2))
>
> bst <- boot.stepAIC(strt,dat,B=50,alpha=0.05,direction='forward',steps=limit,
>                     scope=list(lower=frm1,upper=frm2))
>
> b1 <- bst$Covariates
> ball <- data.frame(b1)
> names(ball)=unlist(trg)
>
> Any ideas?
>
> Cheers,
> SOH
>
>
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>
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