如何在存在可选参数的情况下处理省略号(...)？

Question

当我在函数定义中使用可选参数时,我的省略号有问题.为了澄清,我定义了以下功能:

func1 <- function (x) (x-2)^2

func3 <- function (fun, arg.curve.user){
  arg.curve.user$expr <-  substitute(func1)
  arg.curve.default <- list(col = "blue", n = 1000, main = "This is a test")
  arg.curve <- modifyList (arg.curve.default, arg.curve.user)
  do.call("curve", arg.curve)
}

# optimizes func1 and call func2 to plot func1
func2 <- function (lb, ub, n.restarts = 5, n.sim = 10, ...){
  arg.curve.user <- as.list(substitute(list(...)))
  output <- gosolnp(fun = func1, LB = lb, UB = ub,  n.restarts =  n.restarts, 
  n.sim =  n.sim)$par
  func3(fun = func1, arg.curve.user = arg.curve.user)
   return(output)
}

通过调用func2,func1被优化并且还通过func3调用绘制(需要包Rsolnp).

func2 ( lb = 0, ub = 8, n.restarts = 5, n.sim = 10, n = 200, from = 0, to = 8)

但假设用户拼写错误n.restarts并写道nrestarts:

func2 ( lb = 0, ub = 8, nrestarts = 5, n.sim = 10, n = 200, from = 0, to = 8)

在这种情况下,我希望R实施以下计划来处理缺席n.restarts:

1. 将默认值(即5)分配给n.restarts作为可选参数
2. 最后声明一个警告:"nrestarts"不是图形参数

但这不会发生, R会将n(200)的值赋予n.restarts而不是!!

任何人都可以帮我解决这个问题吗？

非常感谢

Answer 1

当n参数n.restarts不是由用户提供时,它是部分匹配参数.相反,与@Andrie(当然会有效)的建议相反,有一种机制可以让你以参数n和论证的方式继续n.restarts.诀窍是把你想匹配参数完全相同 后的....

func2 <- function (lb, ub, ..., n.restarts = 5, n.sim = 10){
  writeLines(paste("Value of `n.restarts` is", n.restarts))
  arg.curve.user <- as.list(substitute(list(...)))
  output <- gosolnp(fun = func1, LB = lb, UB = ub,  n.restarts =  n.restarts, 
                    n.sim =  n.sim)$par
  func3(fun = func1, arg.curve.user = arg.curve.user)
  output
}

在使用中,这给出:

> func2 (lb = 0, ub = 8, n.restarts = 2, n.sim = 10, n = 200,
+        from = 0, to = 8)
Value of `n.restarts` is 2          <---- Here!

Iter: 1 fn: 6.926e-15    Pars:  2.00000
Iter: 2 fn: 2.501e-15    Pars:  2.00000
solnp--> Completed in 2 iterations

Iter: 1 fn: 8.336e-16    Pars:  2.00000
Iter: 2 fn: 8.336e-16    Pars:  2.00000
solnp--> Completed in 2 iterations
[1] 2
> func2 (lb = 0, ub = 8, nrestarts = 2, n.sim = 10, n = 200,
+        from = 0, to = 8)
Value of `n.restarts` is 5          <---- Here! Default

Iter: 1 fn: 2.83e-15     Pars:  2.00000
Iter: 2 fn: 2.5e-15  Pars:  2.00000
solnp--> Completed in 2 iterations

Iter: 1 fn: 2.037e-15    Pars:  2.00000
Iter: 2 fn: 2.037e-15    Pars:  2.00000
solnp--> Completed in 2 iterations

Iter: 1 fn: 1.087e-15    Pars:  2.00000
Iter: 2 fn: 1.087e-15    Pars:  2.00000
solnp--> Completed in 2 iterations

Iter: 1 fn: 8.558e-16    Pars:  2.00000
Iter: 2 fn: 8.558e-16    Pars:  2.00000
solnp--> Completed in 2 iterations

Iter: 1 fn: 7.147e-16    Pars:  2.00000
Iter: 2 fn: 7.147e-16    Pars:  2.00000
solnp--> Completed in 2 iterations
[1] 2
Warning messages:
1: In plot.window(...) : "nrestarts" is not a graphical parameter
2: In plot.xy(xy, type, ...) : "nrestarts" is not a graphical parameter
3: In axis(side = side, at = at, labels = labels, ...) :
  "nrestarts" is not a graphical parameter
4: In axis(side = side, at = at, labels = labels, ...) :
  "nrestarts" is not a graphical parameter
5: In box(...) : "nrestarts" is not a graphical parameter
6: In title(...) : "nrestarts" is not a graphical parameter