CODEWITHSUNDEEP
rparsingeval
deschen
deschen

Reputation: 10996

How to correctly evaluate a literal character vector

Let's assume I have the following object in R:

QXX_my_vector <- "c(\"Element 1\", \"Element 2\", \"Element 3\", \"Element 4\")"

I want to turn this into a true character vector containing the four elements.

I can do this via eval(parse(text = QXX_my_vector)) which gives:

# [1] "Element 1" "Element 2" "Element 3" "Element 4"

My problem/question is: I want to dynamically pass the text element into the parse function, i.e.:

question_stem = "QXX"
eval(parse(text = paste0(question_stem, "_my_vector")))

However, this gives:

# [1] "c(\"Element 1\", \"Element 2\", \"Element 3\", \"Element 3\")"

I also tried to wrap the paste0 part into a sym function, but this gives the same result.

Any ideas?

Upvotes: 1

Views: 292

Answers (2)

akrun
akrun

Reputation: 887088

We can use str_extract

library(stringr)
 str_extract_all(get(paste0(question_stem, "_my_vector")), '(?<=")[^",)]+')[[1]]
[1] "Element 1" "Element 2" "Element 3" "Element 4"

Upvotes: 0

GKi
GKi

Reputation: 39657

You have to use get to get an object with the given name.

eval(parse(text = get(paste0(question_stem, "_my_vector"))))
#[1] "Element 1" "Element 2" "Element 3" "Element 4

Upvotes: 1

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