?model.frame
?model.matrix
`S Programming' by Venables & Ripley (2000).
On Fri, 13 Dec 2002, Ravi Varadhan wrote:
Hi:
I'd like to get the objects corresponding to the elements in a
formula,> from a data frame. For example, suppose I would like to
make a
function call, such as follows:
myfunc(formula="y ~ x1 + x2 + log(x3)" , data=mydata)
This function will get the vector objects y, x1, x2, and log(x3)
from> the data frame "mydata" to form the design matrix and then
perform a
maximum likelihood estimation of the regression parameters.
My questions is, how do I get the the vector objects y, x1, x2, and
log(x3),specified the formula, from the data frame "mydata"?
BTW, that's not precisely how formulae in R work.
--
Brian D. Ripley, ripley at 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 272860 (secr)
Oxford OX1 3TG, UK Fax: +44 1865 272595