Patrik Waldmann <[EMAIL PROTECTED]> writes: > Hello again, > > I was too quick before. What I was looking for was a function that > constructs the design (or incidence) matrix (X in a linear model) from a > factor. Uwe Ligges suggested using model.matrix and this does almost what I > want, but it is first necessary to construct a data variable. It also asigns > ones to all rows of the first column (because this is set to be the > contrast, not really what I want - see below). Maybe time for a function > that just converts a factor into a design matrix? > > I have a factor > factor<-as.factor(c(1,1,2,2,3,3,3))
That could get you in trouble by masking the factor() function... > and I want a matrix > 1 0 0 > 1 0 0 > 0 1 0 > 0 1 0 > 0 0 1 > 0 0 1 > 0 0 1 f <- factor(c(1,1,2,2,3,3,3)) model.matrix(~f-1) Or, a different approach: diag(3)[f,] -- O__ ---- Peter Dalgaard Blegdamsvej 3 c/ /'_ --- Dept. of Biostatistics 2200 Cph. N (*) \(*) -- University of Copenhagen Denmark Ph: (+45) 35327918 ~~~~~~~~~~ - ([EMAIL PROTECTED]) FAX: (+45) 35327907 ______________________________________________ [EMAIL PROTECTED] mailing list https://www.stat.math.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide! http://www.R-project.org/posting-guide.html
