this may work. X<-data.frame(sapply(X,function(x) as.factor(x))) reg3=lm(Y~.,data=X) dummy.coef(reg3)
Weidong Gu On Sun, Jun 12, 2011 at 4:55 PM, Robert Ruser <robert.ru...@gmail.com> wrote: > Hi, > but I want to get the coefficients for every variables from x1 to x5. > (x1 was an example) > > Robert > > 2011/6/12 Jorge Ivan Velez <jorgeivanve...@gmail.com>: >> Hi Robert, >> >> Try this: >> reg2 <- lm( Y ~ factor(x1) + factor(x2) + factor(x3) + factor(x4) + >> factor(x5) - 1, data = X ) >> cof(ref2) >> HTH, >> Jorge >> >> On Sun, Jun 12, 2011 at 4:40 PM, Robert Ruser <> wrote: >>> >>> Prof. Ripley, thank you very much for the answer but wanted to get >>> something else. There is an example and an explanation: >>> >>> options(contrasts=c("contr.sum","contr.poly")) # contr.sum uses ‘sum >>> to zero contrasts’ >>> Y <- c(6,3,5,2,3,1,1,6,6,6,7,4,1,6,6,6,6,1) >>> X <- structure(list(x1 = c(2L, 3L, 1L, 3L, 3L, 2L, 1L, 1L, 3L, 2L, >>> 3L, 2L, 1L, 1L, 2L, 1L, 2L, 3L), x2 = c(3L, 3L, 2L, 3L, 1L, 3L, >>> 2L, 3L, 2L, 1L, 2L, 2L, 3L, 1L, 2L, 1L, 1L, 1L), x3 = c(1L, 1L, >>> 1L, 1L, 1L, 2L, 1L, 1L, 2L, 1L, 2L, 1L, 2L, 1L, 1L, 2L, 2L, 1L >>> ), x4 = c(1L, 1L, 2L, 2L, 1L, 2L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, >>> 1L, 2L, 2L, 1L, 2L), x5 = c(1L, 1L, 2L, 2L, 3L, 3L, 3L, 2L, 2L, >>> 2L, 1L, 3L, 3L, 1L, 1L, 1L, 2L, 3L)), .Names = c("x1", "x2", >>> "x3", "x4", "x5"), row.names = c(NA, 18L), class = "data.frame") >>> >>> reg <- lm( Y ~ factor(X$x1) + factor(X$x2) + factor(X$x3) + >>> factor(X$x4) + factor(X$x5) ) >>> coef(reg) >>> >>> and e.g. I get two coefficients for variable x1 (3-levels variable) >>> but I would like to get the third. Of course I can calculate a3= >>> -(a1+a2) where a1 and a2 are coefficients of the variable x1. >>> >>> I hope that I manage to explain my problem. >>> >>> Robert >>> >>> 2011/6/12 Prof Brian Ripley <>: >>> > ?dummy.coef >>> > >>> > (NB: 'R' does as you tell it, and if you ask for the default contrasts >>> > you >>> > get coefficients a2 and a3, not a1 and a2. So perhaps you did something >>> > else and failed to tell us? And see the comment in ?dummy.coef about >>> > treatment contrasts.) >>> > >>> > >>> > On Sun, 12 Jun 2011, Robert Ruser wrote: >>> > >>> >> Dear R Users, >>> >> Using lm() function with categorical variable R use contrasts. Let >>> >> assume that I have one X independent variable with 3-levels. Because R >>> >> estimate only 2 parameters ( e.g. a1, a2) the coef function returns >>> >> only 2 estimators. Is there any function or trick to get another a3 >>> >> values. I know that using contrast sum (?contr.sum) I could compute a3 >>> >> = -(a1+a2). But I have many independent categorical variables and I'm >>> >> looking for a fast solution. >>> >> >>> >> Robert >>> >> >>> >> ______________________________________________ >>> >> 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. >>> >> >>> > >>> > -- >>> > Brian D. Ripley, rip...@stats.ox.ac.uk >>> > Professor of Applied Statistics, http://www.stats.ox.ac.uk/~ripley/ >>> > University of Oxford, Tel: +44 1865 272861 (self) >>> > 1 South Parks Road, +44 1865 272866 (PA) >>> > Oxford OX1 3TG, UK Fax: +44 1865 272595 >>> > >>> >>> ______________________________________________ >>> 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. > ______________________________________________ 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.