Hi,
If you have the formula stored in a string, you could also use
as.formula in your call to lm, like this:
form <- "x ~ y + z"
lm(as.formula(form))
HTH,
Ivan
Le 1/23/2011 21:38, Joshua Wiley a écrit :
Hi Paul,
You need to pass the formula object, not a string. If you have a
function that is passing one of its arguments down to lm(), just pass
the argument directly, no need to do anything special. Here are some
examples using a built in dataset:
## wrapper function
foo<- function(fooform, ...) {
summary(lm(formula = fooform, ...))
}
## seeing it in action
foo(mpg ~ hp * wt, data = mtcars)
## save a formula in an object
myform<- mpg ~ hp * wt
## pass the object to foo() which passes it down
foo(myform, data = mtcars)
## pass the formula object "myform" directly to lm()
summary(lm(myform, data = mtcars))
Do one of those answer your question or do what you want?
Hope this helps,
Josh
On Sun, Jan 23, 2011 at 8:46 AM, Paul Evans<[email protected]> wrote:
Hi,
I had a function that looked like:
diff<- lm(x ~ y + z)
How can I pass the argument to the 'lm' function on the fly? E.g., if I pass it
in as a string (e.g. "x ~ y + z"), then the lm function treats it as a string
and not a proper argument.
many thanks
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