Thanks for the tips. I'll give them a try! On Sat, Jun 18, 2011 at 12:07 PM, Dennis Murphy <djmu...@gmail.com> wrote:
> Much better..nice! > > Dennis > > On Sat, Jun 18, 2011 at 1:53 AM, Dimitris Rizopoulos > <d.rizopou...@erasmusmc.nl> wrote: > > maybe another way is by reconstructing the formula using paste(), e.g., > > > > data <- data.frame(y = rnorm(5), x1 = runif(5), > > z = runif(5), age = runif(5)) > > > > nameRsp <- "y" > > nams <- names(data) > > namsX <- nams[!nams %in% nameRsp] > > form <- as.formula(paste(nameRsp, "~" , > > paste("log(", namsX, ")", sep = "", collapse = "+"))) > > > > lm(form, data) > > > > > > I hope it helps. > > > > Best, > > Dimitris > > > > > > On 6/18/2011 10:41 AM, Dennis Murphy wrote: > >> > >> Yes, it's possible, but if you want to do prediction on future > >> x-values, you will likely have a problem. > >> > >> One way to do it would be something like (assuming y is the first column > >> of dat) > >> > >> reg<- lm(y ~ log(as.matrix(dat[, -1])), dat) > >> > >> but the output would be pretty ugly (see summary(reg)). Another would > >> be to construct the matrix outside the data frame and do something > >> like > >> > >> X<- log(as.matrix(dat[, -1])) > >> reg<- lm(dat$y ~ X) > >> > >> There may be better ways, though... > >> > >> Dennis > >> > >> On Fri, Jun 17, 2011 at 11:08 PM, Scott Fortmann-Roe<scot...@gmail.com> > >> wrote: > >>> > >>> Hi, > >>> > >>> I would like to do a regression like: > >>> > >>> reg<- lm(y~log(.), data) > >>> > >>> where the log function is applied to "." in the form: > >>> > >>> log(x1)+ log(x2)+ log(x3)... > >>> > >>> instead of in the form > >>> > >>> log(x1+x2+x3+...) > >>> > >>> > >>> Is this possible? > >>> > >>> Thank you, > >>> Scott > >>> > >>> [[alternative HTML version deleted]] > >>> > >>> ______________________________________________ > >>> R-help@r-project.org mailing list > >>> https://stat.ethz.ch/mailman/listinfo/r-help > >>> PLEASE do read the posting guide > >>> http://www.R-project.org/posting-guide.html > >>> and provide commented, minimal, self-contained, reproducible code. > >>> > >> > >> ______________________________________________ > >> R-help@r-project.org mailing list > >> https://stat.ethz.ch/mailman/listinfo/r-help > >> PLEASE do read the posting guide > >> http://www.R-project.org/posting-guide.html > >> and provide commented, minimal, self-contained, reproducible code. > >> > > > > -- > > Dimitris Rizopoulos > > Assistant Professor > > Department of Biostatistics > > Erasmus University Medical Center > > > > Address: PO Box 2040, 3000 CA Rotterdam, the Netherlands > > Tel: +31/(0)10/7043478 > > Fax: +31/(0)10/7043014 > > Web: http://www.erasmusmc.nl/biostatistiek/ > > > [[alternative HTML version deleted]] ______________________________________________ R-help@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.