Suppose you just wanted variables 2,4 and 7 (which are in columns 3, 5 and 8, respectively). Then you could do this:
lm(X1 ~ X2 + X4 + X7, x) or lm(X1 ~., x[,c(2,4,7)+1]) Date: Tue, 21 Sep 2004 12:27:38 +0800 From: rongguiwong <[EMAIL PROTECTED]> To: <[EMAIL PROTECTED]> Subject: Re: [R] how to take this experiment with R? �� 2004��9��21�� ���ڶ� 12:10��Gabor Grothendieck д���� it works. but i come across anather problem. i just wnat to select 3 of the best indepent variables. but the reslut from step(lm(X1 ~., x)) is : Step: AIC= -37.64 X1 ~ X2 + X3 + X4 + X8 + X10 + X11 + X13 + X14 + X15 + X18 + X21 + X22 + X25 + X26 + X27 + X29 + X30 + X31 Df Sum of Sq RSS AIC <none> 11.014 -37.642 - X8 1 0.559 11.574 -37.165 - X27 1 0.867 11.881 -35.853 - X2 1 0.971 11.986 -35.416 - X18 1 0.978 11.992 -35.390 - X31 1 1.122 12.136 -34.793 - X10 1 1.400 12.414 -33.659 - X15 1 1.563 12.578 -33.005 - X29 1 1.608 12.622 -32.828 - X13 1 1.805 12.819 -32.055 - X30 1 1.880 12.894 -31.763 - X4 1 2.368 13.382 -29.906 - X14 1 2.495 13.509 -29.433 - X3 1 2.983 13.997 -27.659 - X22 1 2.999 14.013 -27.600 - X21 1 3.377 14.391 -26.271 - X25 1 4.323 15.338 -23.086 - X11 1 6.775 17.789 -15.672 - X26 1 7.232 18.246 -14.403 > You can express your model like this: > > > > lm(X1 ~., x) > > > > ?formula gives some help on formulas although the . notation > > above does not seem to be referred to there. > > > > > > Date: Tue, 21 Sep 2004 11:52:04 +0800 > > From: rongguiwong <[EMAIL PROTECTED]> > > To: <[EMAIL PROTECTED]> > > Subject: [R] how to take this experiment with R? > > > > i want to generate 30 independent variables and 1 dependent variable,each > has > > 50 draws from a unit normal distribution. > > then, searching for the independent variables that together would do the > best > > job for fitting the denpendent variabe. > > > > my way to generate the data is. > > x<-data.frame(matrix(rnorm(1550),c(50,31))) > > but is there more better way to do it? > > > > i want to use the followling is to search the model. > > model<-step(lm(X1~X2+X3+X4.....)) > > but i don't know the to express the formula with lm function.i think there > is > > a way the express it efficently. > > i try ?lm .but on result be found. > > > > any help is welcome! > ______________________________________________ [EMAIL PROTECTED] mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide! http://www.R-project.org/posting-guide.html
