[R] call lattice function in a function passing
Ryan Hafen
rhafen at purdue.edu
Thu Dec 11 16:13:57 CET 2008
>
> If however I wanted to call the function "densityplot" within a function and
> pass the "groups" argument as an argument of that function, how would I have
> to proceed? It is not as straightforward as
>
> f <- function(data, groupvar) {
> densityplot(~ x, data, groups = groupvar)
> }
>
> probably because the lattice function "densityplot.formula" preprocesses
> the "groups" argument with
>
> groups <- eval(substitute(groups), data, environment(formula))
>
> It there a way how I could pass the "groups" argument in the function "f"?
Here's one approach. Pass the 'groups' variable as a character, then find
that variable in the data frame and rename it.
d <- data.frame(x = rnorm(100), y = c("a", "b"))
f <- function(data, groupvar) {
names(data)[which(names(data) == groupvar)] <- "gp"
densityplot(~ x, data, groups = gp)
}
f(d, groupvar="y")
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