Thank you Bert and Prof. Ripley for your feedback. I did read the language documentation and it was not entirely clear to me, but I'm one of those people that has to read and digest something before it clicks. However, I did realize that the issue with "call"and "formula" was not the real reason why my program did not work. The real reason was much more trivial: I put the arguments inside the systemfit function out of order. Eventually, I figured it out. The good thing about this is that I learned about the existence of the R language documentation. Thank you again both! Rita ===================================== "If you think education is expensive, try ignorance."--Derek Bok
---------------------------------------- > Date: Sat, 25 Jun 2011 05:59:40 +0100 > From: rip...@stats.ox.ac.uk > To: gunter.ber...@gene.com > CC: ritacarre...@hotmail.com > Subject: Re: [R] What does class "call" mean? How do I make class "formula" > into a "call"? > > This is really a misleading subject: it is already a call! From > ?class > > Many R objects have a ‘class’ attribute, a character vector giving > the names of the classes from which the object _inherits_. If the > object does not have a class attribute, it has an implicit class, > ‘"matrix"’, ‘"array"’ or the result of ‘mode(x)’ (except that > integer vectors have implicit class ‘"integer"’). > > So, simply remove the class if you want the mode: but anything which > needs to know this is call will be looking at the mode and not the > class. > > > zz <- ~x > > class(zz) > [1] "formula" > > mode(zz) > [1] "call" > > And see ?mode and ?call. Formulae and calls which are not formulae > are completely different: you cannot coerce one to the other. > > > On Fri, 24 Jun 2011, Bert Gunter wrote: > > > Well, this is kind of complicated. The first place you should go for > > help is not this list, but the R docs. Specfically ?call. This > > assumes familiarity with R's (S3) class system and language structure, > > however.. For this, I suggest ?UseMethod and consulting the R Language > > Definition Manual. > > > > Perhaps some brave soul on this list will attempt a short explanation > > in reply. But I am not (s)he. > > > > Cheers, > > Bert > > > > Oh -- as for specific suggestions, I think you need to do what the > > posting guide asks and provide a minimal reproducible example to give > > people a clearer idea of what's going on. > > > > On Fri, Jun 24, 2011 at 2:58 PM, Rita Carreira <ritacarre...@hotmail.com> > > wrote: > >> > >> I have a list called "tabs" that I would like to have the same > >> structure as my list "eqSystem." The two look like they have the > >> same format but they are different because when I look at their > >> attributes, class(eqSystem[[1]]) is "call" but class(tabs[[1]]) is > >> "formula". I want to have class(tabs[[1]]) as a call too. So what > >> does "call" mean? And how do I make an object of type "formula" be > >> of type "call"? > >> Thank you so much!!!--Rita > >>> class(tabs) > >> [1] "list" > >>> class(tabs[1]) > >> [1] "list" > >>> class(tabs[[1]]) > >> [1] "formula"> class(eqSystem) > >> [1] "list" > >>> class(eqSystem[1]) > >> [1] "list" > >>> class(eqSystem[[1]]) > >> [1] "call" > >> > >> > >> Rita > >> ===================================== > >> "If you think education is expensive, try ignorance."--Derek Bok > >> > >> ______________________________________________ > >> 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. > >> > > > > > > > > -- > > "Men by nature long to get on to the ultimate truths, and will often > > be impatient with elementary studies or fight shy of them. If it were > > possible to reach the ultimate truths without the elementary studies > > usually prefixed to them, these would not be preparatory studies but > > superfluous diversions." > > > > -- Maimonides (1135-1204) > > > > Bert Gunter > > Genentech Nonclinical Biostatistics > > > > ______________________________________________ > > 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. > > > > -- > Brian D. Ripley, rip...@stats.ox.ac.uk > 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 ______________________________________________ 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.
