R中带卷曲的str_subset

Question

我有一个很小的函数，可以使用str_subset读入带有特定字符串的文件，如果我用引号传递参数，它就会起作用，但我想不用引号。我以为我可以用curly curly做到这一点，但是不起作用。

使用引号传递的工作示例：

#creating csv file
library(tidyverse)
write_csv(mtcars, "C:\\Users\\testSTACK.csv")


#reading function
read_in_fun <- function(x) {

  setwd("C:\\Users")
  d <- list.files()   #lists all files in folder
  file <- d %>% 
    str_subset(pattern = x)

  #read in
  df <- read_csv(file)

  arg_name <- deparse(substitute(x)) 
  var_name <- paste("df_new", arg_name, sep = "_") 
  assign(var_name, df, env = .GlobalEnv) 

}

read_in_fun("STACK")

#this works, returns df called:
df_new_"STACK"

现在，如果我尝试使用卷曲方法传递无引号：

read_in_fun <- function(x) {

  setwd("C:\\Users")
  d <- list.files()   #lists all files in folder
  file <- d %>% 
    str_subset(pattern = {{x}})

  #read in
  df <- read_csv(file)

  arg_name <- deparse(substitute(x)) 
  var_name <- paste("df_new", arg_name, sep = "_") 
  assign(var_name, df, env = .GlobalEnv) 

}
read_in_fun(STACK)
#Error in type(pattern) : object 'STACK' not found

我还尝试使用enquo

read_in_fun <- function(x) {

  x_quo <- enquo(x)


  setwd("C:\\Users")
  d <- list.files()   #lists all files in folder
  file <- d %>% 
    str_subset(pattern = !! as_label(x_quo)) #OR !!(x_quo)

  #read in
  df <- read_csv(file)

  arg_name <- deparse(substitute(x)) 
  var_name <- paste("df_new", arg_name, sep = "_") 
  assign(var_name, df, env = .GlobalEnv) 

}
read_in_fun(STACK)
# Error during wrapup: Quosures can only be unquoted within a quasiquotation context.

我想要的输出是一个名为df_new_STACK的df。curly curly可以这样使用吗？谢谢

Answer 1

使用ensym应该可以。

read_in_fun <- function(x) {

  x_sym <- ensym(x)

  d <- list.files()   
  file <- d %>% 
    str_subset(pattern = as_label(x_sym)) 

  #read in
  df <- read_csv(file)

  arg_name <- deparse(substitute(x)) 
  var_name <- paste("df_new", arg_name, sep = "_") 
  assign(var_name, df, env = .GlobalEnv) 

}

read_in_fun(STACK)

df_new_STACK