Hi, I am trying to build a function in which I will pass the contrasts of a linear model as a parameter of the function. The question is how can I pass the contrasts if they are inserted in a object: if I do: tmp=makeContrasts("ctrl-trt", levels=c("ctrl", "trt")) works! if instead I do mycontrast="ctrl-trt" tmp=makeContrasts(mycontrast, levels=c("ctrl", "trt")) it does not and I get the error: Error in eval(expr, envir, enclos) : object "mycontrast" not found There is any trick to pass my contrasts if they are inserted in an object? Thanks Raffaele ---------------------------------------- Prof. Raffaele A. Calogero Bioinformatics and Genomics Unit Dipartimento di Scienze Cliniche e Biologiche c/o Az. Ospedaliera S. Luigi Regione Gonzole 10, Orbassano 10043 Torino tel. ++39 0116705420 Lab. ++39 0116705408 Fax ++39 0119038639 Mobile ++39 3333827080 email: raffaele.calogero at unito.it www: www.bioinformatica.unito.it

Dear Raffaele, > I am trying to build a function in which I will pass the > contrasts of a linear model as a parameter of the function. > The question is how can I pass the contrasts if they are > inserted in a object: > if I do: > tmp=makeContrasts("ctrl-trt", levels=c("ctrl", "trt")) > works! > > if instead I do > mycontrast="ctrl-trt" > tmp=makeContrasts(mycontrast, levels=c("ctrl", "trt")) > it does not and I get the error: > Error in eval(expr, envir, enclos) : object "mycontrast" not found > > There is any trick to pass my contrasts if they are inserted > in an object? Yes, there is: lev <- c("ctrl", "trt") cmd <- paste("tmp <- makeContrasts(", mycontrast, ", levels = lev)", sep = '"') eval(parse(text = cmd)) I personally think that makeContrasts() should accept the contrasts as a string argument only, this would make live much easier (but would probably break a lot of existing scripts). You ran in similar problems if the contrast starts with a digit: cont <- makeContrasts("2h-0h", levels = design) Error in parse(file, n, text, prompt) : syntax error in "2h" hth Gerhard