formula mungeing
Recursively walk the formula performing the replacement:
g <- function(e, ...) {
if (length(e) > 1) {
if (identical(e[[2]], as.name(names(list(...))))) {
e <- eval(e, list(...))
}
if (length(e) > 1) for (i in 1:length(e)) e[[i]] <- Recall(e[[i]], ...)
}
e
}
g(f, lambdas = 2:3)
## y ~ qss(x, lambda = 2L) + qss(z, 3L) + s
On Fri, Oct 23, 2020 at 9:33 AM Koenker, Roger W <rkoenker at illinois.edu> wrote:
Suppose I have a formula like this:
f <- y ~ qss(x, lambda = lambdas[1]) + qss(z, lambdas[2]) + s
I?d like a function, g(lambdas, f) that would take g(c(2,3), f) and produce the new
formula:
y ~ qss(x, lambda = 2) + qss(z, 3) + s
For only two qss terms I have been using
g <- function(lambdas, f){
F <- deparse(f)
F <- gsub("lambdas\\[1\\]",lambdas[1],F)
F <- gsub("lambdas\\[2\\]",lambdas[2],F)
formula(F)
}
but this is ugly and doesn?t extend nicely to more qss terms. Isn?t there some
bquote() magic that can be invoked? Or something else entirely?
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