Dear all Nobody responded to my previous post so far so I try with more offending subject.
I just encountered a strange problem with nls formula. I tried to use nls in cycle but I was not successful. I traced the problem to some parse command. Here is an example DF<-data.frame(x=1:10, y=3*(1:10)^.5+rnorm(10)) coef(lm(log(DF[,2])~log(DF[,1]))) (Intercept) log(DF[, 1]) 0.7437320 0.6831726 # this works coef(nls(y~a*x^b, data=DF, start=list(a=3, b=.7))) a b 2.6412881 0.5545907 # OK, this works too coef(nls(DF[,2]~a*DF[,1]^b, data=DF, start=list(a=3, b=.7))) Error in parse(text = x) : unexpected end of input in "~ " coef(nls(DF[,2]~a*DF[,1]^b, start=list(a=3, b=.7))) Error in parse(text = x) : unexpected end of input in "~ " # but this does not Browse[1]> debug: mf$formula <- as.formula(paste("~", paste(varNames[varIndex], collapse = "+")), env = environment(formula)) Browse[1]> Error in parse(text = x) : unexpected end of input in "~ " > Actually the problem is that with calling nls with DF[,n]~... varNames and varIndex is not correctly specified. I am not sure if this behaviour is a bug or feature. If it is a feature, please help me how to call variables from data frame when using nls inside cycle for (i in ....) result[i,] <- coef(nls( ...., )) Thank you Petr > sessionInfo() R version 2.8.0 Under development (unstable) (2008-05-18 r45723) i386-pc-mingw32 locale: LC_COLLATE=Czech_Czech Republic.1250;LC_CTYPE=Czech_Czech Republic.1250;LC_MONETARY=Czech_Czech Republic.1250;LC_NUMERIC=C;LC_TIME=Czech_Czech Republic.1250 attached base packages: [1] stats grDevices datasets utils graphics methods base other attached packages: [1] nlme_3.1-88 lattice_0.17-7 fun_0.1 loaded via a namespace (and not attached): [1] grid_2.8.0 tools_2.8.0 Petr Pikal [EMAIL PROTECTED] 724008364, 581252140, 581252257 ______________________________________________ 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.