Question

我创建了函数mad_libs，其中将省略号作为参数传递并解压缩。功能“有效”，因为它打印并且显然没有任何问题，但我没有得到我通过的论据。

功能如下：

   mad_libs <- function(...){
            args <- list(...)

            place <- args[["place"]]
            adjective <- args[["adjective"]]
            noun <- args[["noun"]]

            paste("News from", place, "today where", adjective, "students took 
to the streets in protest of the new", noun, "being installed on campus.")
    }

假设我通过mad_libs("NIFLHEIM", "possessed", "fountain")或其他任何参数，总是在“”之间，我得到：

    [1] "News from  today where  students took to the streets in protest 
of the new  being installed on campus."

不打印参数。

我遇到了打印问题，因为我的操作系统是用葡萄牙语编写的，但似乎拼写规则不是问题。

在RStudio上运行R 3.3.1，使用巴西葡萄牙语运行Windows 10。

Answer 1

你应该学习argument matching。

如果您希望位置匹配和名称匹配都有效，可以像这样使用do.call：

mad_libs <- function(...){
  args <- list(...)

  fun <- function(place, adjective, noun)
    paste("News from", place, "today where", adjective, "students took to the streets in protest of the new", noun, "being installed on campus.")

  do.call(fun, args)
}

mad_libs("NIFLHEIM", "possessed", "fountain")
#[1] "News from NIFLHEIM today where possessed students took to the streets in protest of the new fountain being installed on campus."

mad_libs(adjective = "possessed", "NIFLHEIM", "fountain")
#[1] "News from NIFLHEIM today where possessed students took to the streets in protest of the new fountain being installed on campus."

当然，如果没有令人信服的理由来创建args，您可以简单地传递省略号：

mad_libs <- function(...){

  fun <- function(place, adjective, noun)
    paste("News from", place, "today where", adjective, "students took to the streets in protest of the new", noun, "being installed on campus.")

  fun(...)
}

解压缩省略号后的paste（）将不会打印列出的参数

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