This is probably buried somewhere in the R help archives, but I've been
unable to find it, so perhaps the keywords I use here will help bring the
topic to the surface more easily for future users.
 
I want to write my own modeling function (ultimately for some
multidimensional windowing - but this question is on scripting basics).  For
purposes of figuring out my needs, lets just consider writing a function
that takes a formula and a dataset, and outputs the mean of each variable in
the formula model.  So:
 
MyFunction <- function(AFormula, ADataFrame) {
 ...
 }
 
>MyFunction(Y ~ A + B, TheData)
 
would give results something like:
 
Mean of MyData$Y is 5.3
Mean of MyData$A is 3.4
Mean of MyData$B is 8.2
 
QUESTION 1:
How do I determine the terms in the formula within the function?
 
QUESTION 2:
How do I use one of those terms to get to the individual columns, like
MyData$Y ?
 
Thanks!
-Eric
---
Eric Peterson
Vegetation Ecologist
Nevada Natural Heritage Program

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