[R] Passing arguments to glm()
Gabor Grothendieck
ggrothendieck at gmail.com
Fri Jun 30 18:27:18 CEST 2006
This is the same as glm except that
- formula may be of class character in which case its
regarded as the name of the response variable and
the formula defaults to resp ~ Species for that response
- the data frame defaults to iris
- modify as appropriate for your case
myglm <- function (formula, family = gaussian, data,
weights, subset, na.action, start = NULL, etastart, mustart, offset,
control = glm.control(...), model = TRUE, method = "glm.fit",
x = FALSE, y = TRUE, contrasts = NULL, ...) {
cl <- match.call()
cl[[1]] <- as.name("glm")
if (is.character(formula)) {
fo <- . ~ Species ### default formula
fo[[2]] <- as.name(formula)
cl$formula <- fo
}
if (missing(data)) cl$data <- as.name("iris") # default data frame
eval(cl, parent.frame())
}
# test
myglm("Sepal.Length", subset = Petal.Length > mean(Petal.Length))
myglm(Sepal.Length ~ Petal.Length)
myglm("Sepal.Length", subset = 1:100)
On 6/30/06, Christian Bieli <christian.bieli at unibas.ch> wrote:
> Hi there
>
> I want to pass arguments (i.e. the response variable and the subset
> argument) in a self-made function to glm.
> Here is one way I can do this:
>
> f.myglm <- function(y,subfact,subval) {
>
> glm(d.mydata[,y]~d.mydata[,'x1'],family=binomial,subset=d.mydata[,subfact]==subval)
> }
>
> > str(d.mydata)
> `data.frame': 15806 obs. of 3 variables:
> $ y : Factor w/ 2 levels "no","yes": 1 1 1 1 1 1 1 NA 1 1 ...
> $ x1: Factor w/ 2 levels "no","yes": 2 2 1 2 2 2 2 2 2 2 ...
> $ x2: Factor w/ 2 levels "no","yes": 1 1 1 1 1 2 2 1 2 2 ...
>
> > f.myglm('y','x2','yes')
>
> But is there a way I can pass the arguments and use the data argument of
> glm()?
> In a naive way of thinking I'd like to something like this:
> f.myglm <- function(y,sub) {
> glm(y~x1,family=binomial,data=d.mydata,subset=sub)
> }
> > f.myglm(y=y,sub=x2=='yes')
>
> I know that's not possible, because the objects y and x2 are not defined
> in the user workspace.
> So, something like passing the arguments as an expression and evaluate
> it in the glm function should work, but I didn't manage to do it.
>
> I'd appreciate your advice.
> Christian
>
> > R.version
> _
> platform i386-pc-mingw32
> arch i386
> os mingw32
> system i386, mingw32
> status
> major 2
> minor 2.1
> year 2005
> month 12
> day 20
> svn rev 36812
> language R
>
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