Hi,
May be this helps:
set.seed(232)
mat1<-matrix(sample(1:100,80,replace=TRUE),ncol=8) #with 8 columns
dat1<-data.frame(mat1)
?names(dat1)[1]<-"Y"
?form1<-as.formula(paste("Y~",paste(names(dat1)[2:8],collapse="+")))
#should change "8" to "400"
fit.final<-lm(form1,data=dat1)
fit.final
#Call:
#lm(formula = form1, data = dat1)
#
#Coefficients:
#(Intercept)?????????? X2?????????? X3?????????? X4?????????? X5?????????? X6?
# 143.763081??? -0.009030??? -1.844810???? 1.436647??? -0.005407??? -0.050101?
#???????? X7?????????? X8?
#?? 0.563285??? -1.901918?
A.K.
________________________________
From: farnoosh sheikhi <farnoosh_81 at yahoo.com>
To: arun <smartpink111 at yahoo.com>
Sent: Thursday, November 15, 2012 6:14 PM
Subject: Stepwise
Hi there,
I want to apply the following code fo my data with 400 predictors.
I was wondering if there is 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?