R help - Nov 2012 - Step-wise method for large dimension

Hi ,

I want to apply the following code fo my data with 400 predictors.
I was wondering if there ia an alternative way instead of typing 400 predictors
for the following code.
I really appreciate your help.

fit0<-lm(Y~1, data= mydata)
fit.final<- lm(Y~X1+X2+X3+.....+X400, data=mydata) ???
step(fit0, scope=list(lower=fit0, upper=fit.final), data=mydata,
direction="forward")
step(fit.final, scope=list(lower=fit.final, upper=fit0), data=mydata,
direction="backward")
 
Best,Farnoosh Sheikhi
	[[alternative HTML version deleted]]

Probably you just want

Y ~ .

where "." means everything which doesn't appear elsewhere in the
formula.

Michael

On Thu, Nov 15, 2012 at 8:45 PM, farnoosh sheikhi <farnoosh_81 at
yahoo.com> wrote:
>
>
> Hi ,
>
> I want to apply the following code fo my data with 400 predictors.
> I was wondering if there ia an alternative way instead of typing 400
predictors for the following code.
> I really appreciate your help.
>
> fit0<-lm(Y~1, data= mydata)
> fit.final<- lm(Y~X1+X2+X3+.....+X400, data=mydata) ???
> step(fit0, scope=list(lower=fit0, upper=fit.final), data=mydata,
direction="forward")
> step(fit.final, scope=list(lower=fit.final, upper=fit0), data=mydata,
direction="backward")
>
> Best,Farnoosh Sheikhi
>         [[alternative HTML version deleted]]
>
>
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