[R] Passing arguments to glm()

[Gabor Grothendieck]

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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