If I have two factors A and B with levels '1','2','3' and '1','4','6','8' recpectively (note the gaps in the second one). As factors, the levels are named as above while of course the internal codes are (1,2,3) and (1,2,3,4) respectively. I want to make a design matrix of these as one would in a linear model except I can't use lm or glm since the error distribution is not tractable. So I generate an overall factor as 10*A+B (for example) then the internal codes and levels become 11,12,13,14,21,22,23,24,31,32,33,34. I don't mind the internal codes, but is there a neater way of generating the lm-type of factor levels a A*B to give the levels '11','14','16','18','21','24','26','28','31','34','36','38'? Better still would be to assign proper labels to the levels and get factors a 'A1.B1','A1.B2' etc., basically mimicking the standard notation. Is there a proper way to do this other than for-looping and pasting? I don't really want to create a hand-mapping because it is not robust to changes. \John -.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.- r-help mailing list -- Read http://www.ci.tuwien.ac.at/~hornik/R/R-FAQ.html Send "info", "help", or "[un]subscribe" (in the "body", not the subject !) To: r-help-request at stat.math.ethz.ch _._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._
Design matrix labels
2 messages · John Logsdon, Thomas Lumley
On Mon, 25 Jan 1999, John Logsdon wrote:
If I have two factors A and B with levels '1','2','3' and '1','4','6','8' recpectively (note the gaps in the second one). As factors, the levels are named as above while of course the internal codes are (1,2,3) and (1,2,3,4) respectively. I want to make a design matrix of these as one would in a linear model except I can't use lm or glm since the error distribution is not tractable.
You can still use model.frame() and model.matrix() to create design matrices from formulas. mf<-model.frame(~A+B) mmat<-model.matrix(~A+B,mf) If your factors A and B are in a data frame you can use the data= argument to model.frame(). This is what glm() and lm() do internally. Thomas Lumley Assistant Professor, Biostatistics University of Washington, Seattle -.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.- r-help mailing list -- Read http://www.ci.tuwien.ac.at/~hornik/R/R-FAQ.html Send "info", "help", or "[un]subscribe" (in the "body", not the subject !) To: r-help-request at stat.math.ethz.ch _._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._