Suggestions for manipulating formula objects

On Wed, 20 Apr 2005 rlee@fpcc.net wrote:

I'm trying to manipulate/change a formula prior to passing it to another
function.  A simplified example:

User passes formula to my function: y~x
My function does: lm(transform(y)~x)

Here, transform() is added to the model's response.

What is the best way to accomplish this?

One way is

formula[[2]]<-substitute(transform(y),list(y=formula[[2]]))

fo <- y ~ x
update(fo, transform(.) ~ .)