Thanks for your help, I managed to get it working like this:
fml<-as.formula(paste("y ~", paste(PCnames, collapse="+"))) y = class.ind(grp[outgroup]) z1=multinom(formula = fml, data=data.frame(scores)) Daniel Crouch **********QUOTE:******** Forget eval(parse(text = )) See ?as.formula ?update.formula and try out the example() s there. HTH, Chuck On Mon, 16 Feb 2009, Crouch, Daniel wrote: > > Hi, > > > > I am having difficulty entering a 'programmable' argument into the multinom > > function from the nnet package. Interactively, I can get the function to > > work fine by calling it this way: > > > > z1=multinom(formula = class.ind(grp[-outgroup])~ (PC1 + PC2 + PC3), > > data=data.frame(scores)) > > > > However I need to be able to change the number of variables I am looking > > for in 'scores' and so am trying to call it this way... > > > > z1=multinom(formula = class.ind(grp[-outgroup])~ eval(parse(text=PCnames)), > > data=data.frame(scores)) > > > > ...where, for example, PCnames = c("PC1", "+", "PC2", "+", "PC3") > > > > This gives no error messages, but only the last variable (in this case PC3) > > gets considered in the model. z1 looks like this: > > > > (Intercept) eval(parse(text = PCnames)) > > 2 3.530352 -116.87140 > > 3 -1.308613 13.59134 > > 4 3.662172 -57.52198 > > 5 -1.216041 -242.38827 > > 6 -9.377894 -367.71614 > > 7 -3.145738 -286.19766 > > > > Rather than this: > > > > (Intercept) PC1 PC2 PC3 > > 2 288.97131 889.281 3776.5837 -2105.751 > > 3 -712.53519 2775.663 8490.5724 8602.834 > > 4 229.17772 4234.950 329.6995 -2182.238 > > 5 85.54585 -3036.657 3968.2517 -3450.070 > > 6 -676.55377 -9545.785 2422.5340 -7183.686 > > 7 -631.91921 10997.432 -3310.2905 -5348.513 > > > > Any help would be much appreciated. > > > > Thanks, > > Daniel Crouch > > > > > > Daniel Crouch > > Research Student > > Department of Medical & Molecular Genetics > > King's College London > > 8th Floor, Tower Wing > > Guy's Hospital > > London SE1 9RT > > United Kingdom > > ______________________________________________ > > 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. > > Charles C. Berry (858) 534-2098 Dept of Family/Preventive Medicine E mailto:cbe...@tajo.ucsd.edu UC San Diego http://famprevmed.ucsd.edu/faculty/cberry/ La Jolla, San Diego 92093-0901 Daniel Crouch Research Student Department of Medical & Molecular Genetics King's College London 8th Floor, Tower Wing Guy's Hospital London SE1 9RT United Kingdom ______________________________________________ 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.