如何通过 ZC1C425268E68385D1AB50741C 将 function arguments 集中到 R 中的向量中？

Question

I have some R-function f , which fixes some parameters of some other function target (thanks to GKi for help ):

target <- function(b1,b2,l1,l2,l3,o1,o2) return((b1+b2+l1+l2+l3+o1+o2)^2)

fixed <- c(b1 = 1, l1 = 2, l2 = 3, l3 = 4, o1 = 5)
variable <- c("o2","b2")

f <- function(fixed, variable) {
  target_new <- function() {}
  formals(target_new) <- setNames(rep(list(bquote()), length(variable)), variable) 
  
  for(i in variable) assign(i, as.symbol(i))
  body(target_new) <- do.call("call", unlist(list("target", mget(variable), as.list(fixed))))
  
  return(target_new)
}

f(fixed,variable)
> function (o2, b2) 
> target(o2 = o2, b2 = b2, b1 = 1, l1 = 2, l2 = 3, l3 = 4, o1 = 5)
> <environment: 0x0000020a8e0c0c88>

I want to maximize target_new by nlm, so I need to concentrate its function arguments into a vector, ie the desired output of f(fixed,variable) is

> function (theta) 
> target(o2 = theta[1], b2 = theta[2], b1 = 1, l1 = 2, l2 = 3, l3 = 4, o1 = 5)

How to modify the above code, so that the function can process the vector theta ?

Please mind that the vectors fixed and variable can be of variable lengths.

Answer 1

You are making this too complicated.

f <- function(fixed, variable) {

  function(theta) {
    args <- c(as.list(theta), as.list(fixed))
    names(args)[seq_along(variable)] <- variable
    do.call(target, args)
  }

}

fun <- f(fixed, variable)

#does it work?
all.equal(
  nlm(fun, p = c(1, 2)),
  nlm(function(theta) target(1,theta[2], 2, 3, 4, 5, theta[1]),
    p = c(1, 2))
)
#[1] TRUE