[R] generating an expression for a formula automatically

From: Maria Montez <montez_at_bu.edu>
Date: Fri 25 Aug 2006 - 07:01:42 EST


Hi!

I would like to be able to create formulas automatically. For example, I want to be able to create a function that takes on two values: resp and x, and then creates the proper formula to regress resp on x.

My code:

fit.main <- function(resp,x) {
 form <- expression(paste(resp," ~ ",paste(x,sep="",collapse=" + "),sep=""))   z <- lm(eval(form))
 z
}
main <- fit.main("y",c("x1","x2","x3","x4"))

and I get this error:
Error in terms.default(formula, data = data) :

        no terms component

Any suggestions?

Thanks, Maria



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