在可选参数存在的情况下如何处理省略号(...)?

问题描述

当我在函数定义中使用可选参数时，省略号存在问题.为了澄清起见，我定义了以下功能:

I have a problem with ellipsis when I use optional arguments in my function definition. To clarify, I define following functions:

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，可对func1进行优化，并通过func3调用进行绘制(需要软件包 Rsolnp ).

By calling func2, func1 is optimized and also plotted through a func3 call (package Rsolnp is required).

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

但是假设用户拼错了n.restarts并编写了nrestarts:

But suppose a user misspells n.restarts and writes 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实施以下计划以应对n.restarts的缺失:

In this case, I expects R to implement the following plans to deal with absence of n.restarts:

1. 将默认值(即5)分配给n.作为可选参数重新启动
2. 最后声明警告:"nrestarts"不是图形参数

但这不会发生，并且 R将n的值(200)分配给n.重新启动！

有人可以帮助我解决此问题吗?

Can anyone help me to fix this problem?

非常感谢

推荐答案

当用户未提供n参数和n.restarts时，它部分匹配.取而代之的是，与@Andrie的建议相反(当然会起作用)，有一种机制可以让您以自己的方式继续使用参数n和参数n.restarts.诀窍是将要匹配的参数完全 放置在...之后.

It is partial matching the n argument to n.restarts when one is not supplied by the user. Instead, and contrary to the advice of @Andrie (which will work, of course), there is a mechanism that allows you to continue in the manner you have with an argument n and and argument n.restarts. The trick is to place arguments you want to match exactly after the ....

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，它给出:

> 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

这篇关于在可选参数存在的情况下如何处理省略号(...)?的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持！