Convert list of non-quoted words into character vector in R

user_4572068 0
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I want to provide a list of words that are unquoted and convert them into a normal string vector in R. Below is an example of what I would like to do, except for the fact that quote only takes 1 object at a time.

ideally the code below should return TRUE from identical, meaning that the words have been converted to a string vector.

notquotedwords<- quote(Person, Woman, Man, Camera, TV)
#Error in quote(Person, Woman, Man, Camera, TV) : 
#  5 arguments passed to 'quote' which requires 1

quotedwords<- c("Person", "Woman", "Man", "Camera", "TV")

identical(notquotedwords, quotedwords)
#ideally the output would be TRUE

This is a MRE, not the actual code, so yes, I understand I could just create a string vector in the first place.

r
3 Answers

You can get the arguments of a function call with some_call[-1], and match.call will return the parent call by default, so you could do

sym_to_char <- function(...){
  as.character(match.call()[-1])
}

notquotedwords <- sym_to_char(Person, Woman, Man, Camera, TV)

quotedwords <- c("Person", "Woman", "Man", "Camera", "TV")

identical(notquotedwords, quotedwords)
#> [1] TRUE

Created on 2022-01-03 by the reprex package (v2.0.1)

With the rlang package, the function ensyms will convert its arguments to symbols.

library(rlang)

sym_to_char <- function(...){
  as.character(ensyms(...))
}

notquotedwords <- sym_to_char(Person, Woman, Man, Camera, TV)

quotedwords <- c("Person", "Woman", "Man", "Camera", "TV")

identical(notquotedwords, quotedwords)
#> [1] TRUE

Created on 2022-01-03 by the reprex package (v2.0.1)

user_67627550

To do this you need the quos and quo_name function from rlang

library(rlang)
notquotedwords<- quos(Person, Woman, Man, Camera, TV)
notquotedwords_char <- as.character(unlist(lapply(notquotedwords, quo_name)))
all.equal(notquotedwords_char , quotedwords)
user_117427530

An undocumented feature of substitute can be used here:

f = function(...) as.character(substitute(...()))

identical(
  c("Person", "Woman", "Man", "Camera", "TV"),
  f(Person, Woman, Man, Camera, TV)
)
[1] TRUE
user_148539070
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