通过 R 中的函数传递字符串

Question

我有以下功能：

example_Foo <- function( ...,FigureFolder){

  # check what variables are passed through the function  
  v_names <- as.list(match.call())
  variable_list <- v_names[2:(length(v_names)-2)] 

  # create file to store figures
  subDir <- c(paste(FigureFolder,"SavedData",sep = "\\"))

}

显然这只是该功能的开始，但我已经遇到了一些问题。在这里，我尝试定义最终希望保存结果的目录。使用该函数的示例是：

weight <- c(102,20,30,04,022,01,220,10)
height <- c(102,20,30,04,022,01,220,10)

catg <- c(102,20,30,04,022,01,220,10)
catg <- matrix(height,nrow = 2)

FigureFolder <- "C:\\exampleDat"

# this is the function
example_Foo(catg,FigureFolder)

这会产生以下错误：

Error in paste(FigureFolder, "SavedData", sep = "\\") : 
  argument "FigureFolder" is missing, with no default

我猜测是由于函数不知道“FigureFolder”是什么，我的问题是如何通过函数传递这个字符串？

Answer 1

因为您不使用命名参数，所以该FigureFolder参数被放入.... 只需使用：

example_Foo(catg, FigureFolder = FigureFolder)

此外：

example_Foo <- function( ...,FigureFolder){

  # check what variables are passed through the function  
  v_names <- as.list(match.call())
  variable_list <- v_names[2:(length(v_names)-2)] 

  # create file to store figures
  subDir <- c(paste(FigureFolder,"SavedData",sep = "\\"))

}

也可以替换为：

example_Foo <- function( ...,FigureFolder){

  # check what variables are passed through the function  
  variable_list = list(...)

  # create file to store figures
  subDir <- c(paste(FigureFolder,"SavedData",sep = "\\"))

}

或者更简单：

example_Foo <- function(variable_list, FigureFolder){
  # create file to store figures
  subDir <- c(paste(FigureFolder,"SavedData",sep = "\\"))

}

保持代码简单可以使其更易于阅读（也适合您自己）并且更易于使用和维护。