[R] formula mungeing
Bert Gunter
bgunter@4567 @end|ng |rom gm@||@com
Fri Oct 23 19:46:17 CEST 2020
I can't compete with Gabor's "elegant" solution, but I don't understand why
your original "ugly" approach doesn't work.
g <- function(lambdas, f){
z <- as.character(f)
for(i in seq_along(lambdas))
z[3]<- sub(paste0("lambdas[", i, "]"), lambdas[i], z[3], fixed =
TRUE)
formula(paste0(z[c(2,1,3)], collapse = " "))
}
> f <- y ~ qss(x, lambda = lambdas[1]) + qss(z, lambdas[2]) + s
> g(1:2, f)
y ~ qss(x, lambda = 1) + qss(z, 2) + s
<environment: 0x7f930e768598>
> f <- y ~ qss(x, lambda = lambdas[1]) + qss(z, lambdas[2]) +
+ qss(z,lambdas[3]) + s
> g(3:1, f)
y ~ qss(x, lambda = 3) + qss(z, 2) + qss(z, 1) + s
<environment: 0x7f930e7404f0>
Is there maybe a problem with the environment of the created formula? Or
have I misunderstood what you wanted?
Cheers,
Bert
Bert Gunter
"The trouble with having an open mind is that people keep coming along and
sticking things into it."
-- Opus (aka Berkeley Breathed in his "Bloom County" comic strip )
On Fri, Oct 23, 2020 at 6:33 AM Koenker, Roger W <rkoenker using 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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