On 20/04/2008 9:40 AM, Ronaldo Reis Junior wrote: > Hi all, > > I have a problem with an object inside a formula in a function that I make. > > I create an object named qvartemp. This object is OK, look the levels: > >> print(levels(qvartemp)) > [1] "baixomedio" "alto" > > Now I create a new object with a new formula: > >> new.form <- as.formula(gsub(qvar,"qvartemp",as.expression(mma$formula))) > > Look this new object: > >> print(new.form) > Riqueza ~ Biomassa * qvartemp > > Now here is the problem, I try to update an existing model (mma) changing the > formula by the new.form > > mmaa <- update(mma,new.form) > > But my function is aborted with this message: > > Error in eval(expr, envir, enclos) : object "qvartemp" not found > > If I create this object qvartemp in R section manually it my function work, > because it get the object from my workspace (but it is usefull just for > testing), but my function dont find this object qvartemp created inside the > function. > > If I run all my function line by line without use the function it work, I > think that is because in this case the object is created in my workspace. But > when I run a function the object is created only in memory (not in my > workspece) and in this case update dont find this object. > > Anybody can suggest any Idea to fix it? I necessary I send my function and a > example.
Formulas have attached environments; that's where they look for the variables they use. You created new.form, but didn't give it the environment of the old one. I think all you need is environment(new.form) <- environment(mma$formula) Duncan Murdoch ______________________________________________ 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.
