Re: [R] Some questions about R's modelling algebra

2010-07-05 Thread Kingsford Jones
On Fri, Jul 2, 2010 at 8:16 AM, Hadley Wickham wrote: >> ?formula in R 2.9.2 says in para 2: >> "The %in% operator indicates that the terms on its left are nested >> within those on the right. For example a + b %in% a expands to the >> formula a + a:b. " > > Ooops, missed that.  So b %in% a = a:b,

Re: [R] Some questions about R's modelling algebra

2010-07-02 Thread Adrian Waddell
> Hadley Wickham rice.edu> > > Where is %in% documented within R? I'm pretty sure it's a different > action to ?"%in%, and it's not mentioned in ?formula You find the documentation for operators like <-, %in%, if, etc by putting the operators between qoutes ?"%in%" ?"<-" ?"if" Regards, A

Re: [R] Some questions about R's modelling algebra

2010-07-02 Thread Thomas Lumley
On Fri, 2 Jul 2010, Hadley Wickham wrote: Hi all, In preparation for teaching a class next week, I've been reviewing R's standard modelling algebra. I've used it for a long time and have a pretty good intuitive feel for how it works, but would like to understand more of the technical details. T

Re: [R] Some questions about R's modelling algebra

2010-07-02 Thread RICHARD M. HEIBERGER
Hadley, The S language modeling language was designed with Wilkinson and Rogers in mind. The notation was changed from their paper to retain consistency with the parsing rules for ordinary algebra in S. I think of ":" as an indicator of an indexing system into the dummy variables. It is not an

Re: [R] Some questions about R's modelling algebra

2010-07-02 Thread Hadley Wickham
> ?formula in R 2.9.2 says in para 2: > "The %in% operator indicates that the terms on its left are nested > within those on the right. For example a + b %in% a expands to the > formula a + a:b. " Ooops, missed that. So b %in% a = a:b, and that's what's meant by "different coding". Hadley -- A

Re: [R] Some questions about R's modelling algebra

2010-07-02 Thread S Ellison
>>> Hadley Wickham 02/07/2010 14:59:53 >>> > Where is %in% documented within R? I'm pretty sure it's a different >action to ?"%in%, and it's not mentioned in ?formula ?formula in R 2.9.2 says in para 2: "The %in% operator indicates that the terms on its left are nested within those on the righ

[R] Some questions about R's modelling algebra

2010-07-02 Thread Hadley Wickham
Hi all, In preparation for teaching a class next week, I've been reviewing R's standard modelling algebra. I've used it for a long time and have a pretty good intuitive feel for how it works, but would like to understand more of the technical details. The best (online) reference I've found so far