Try not to use the name of an R object ... the error is caused by using 'df' as the second argument to eval().
It works with DF in place of df. I don;t understand your subject line: that is not the error message you received. On Mon, 15 Aug 2005, Adaikalavan Ramasamy wrote: > I am trying to replicate the first example from stepAIC from the MASS > package with my own dataset but am running into error. If someone can > point where I have gone wrong, I would appreciate it very much. > > Here is an example : > > set.seed(1) > df <- data.frame( x1=rnorm(1000), x2=rnorm(1000), x3=rnorm(1000) ) > df$y <- 0.5*df$x1 + rnorm(1000, mean=8, sd=0.5) > # pairs(df); head(df) > > lo <- aov( y ~ 1, data=df ) > hi <- aov( y ~ .^2, data=df ) > mid <- aov( y ~ x2 + x3, data=df ) > > Running any of the following commands > > stepAIC( mid, scope=list(upper = ~x1 + x2 + x3 , lower = ~1) ) > stepAIC( mid, scope=list(upper = hi , lower = lo) ) > addterm( mid, ~ x1 + x2 + x3 ) > addterm( lo, hi ) > > gives the same error message : > Error in eval(expr, envir, enclos) : invalid second argument > > Here is a traceback of the first failed command : > 14: eval(predvars, data, env) > 13: model.frame.default(formula = y ~ x2 + x3 + x1, data = df, > drop.unused.levels = TRUE) > 12: model.frame(formula = y ~ x2 + x3 + x1, data = df, drop.unused.levels = > TRUE) > 11: eval(expr, envir, enclos) > 10: eval(mf, parent.frame()) > 9: lm(formula = y ~ x2 + x3 + x1, data = df, method = "model.frame") > 8: eval(expr, envir, enclos) > 7: eval(fcall, env, parent.frame()) > 6: model.frame.lm(fob, xlev = object$xlevels) > 5: model.frame(fob, xlev = object$xlevels) > 4: stats:::add1.lm(object, scope = scope, scale = scale) > 3: addterm.lm(fit, scope$add, scale = scale, trace = max(0, trace - 1), k = > k, ...) > 2: addterm(fit, scope$add, scale = scale, trace = max(0, trace - 1), k = k, > ...) > 1: stepAIC(mid, scope = list(upper = ~x1 + x2 + x3, lower = ~1)) > > Any pointers would be much appreciated. Thank you. > > Regards, Adai > > ______________________________________________ > [email protected] mailing list > https://stat.ethz.ch/mailman/listinfo/r-help > PLEASE do read the posting guide! http://www.R-project.org/posting-guide.html > -- Brian D. Ripley, [EMAIL PROTECTED] Professor of Applied Statistics, http://www.stats.ox.ac.uk/~ripley/ University of Oxford, Tel: +44 1865 272861 (self) 1 South Parks Road, +44 1865 272866 (PA) Oxford OX1 3TG, UK Fax: +44 1865 272595 ______________________________________________ [email protected] mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide! http://www.R-project.org/posting-guide.html
