CODEWITHSUNDEEP
r
Apostolos Polymeros
Apostolos Polymeros

Reputation: 843

variable hidden within a text

I would like to ask if there is a way to see a variable hidden within a text.

if I run 

k <- eval(expression(v <- 1))

then I get v equal to 1.

But how does it work if I have

k <- "v <- 1"

Thank you, in advance

Upvotes: 1

Views: 85

Answers (2)

Joshua Ulrich
Joshua Ulrich

Reputation: 176648

Use parse(text=k) to create an expression, then evaluate it:

eval(parse(text=k))
v
# [1] 1

Upvotes: 5

Jeff Allen
Jeff Allen

Reputation: 17517

Checkout the eval and evalq commands if you're wanting to evaluate the code.

If you just want to find any string before an <- operator, I suppose you could use something like:

regexpr("(.*)[\\s]*<-", "a <- 1", perl=TRUE)

which would return the start index of the variable name, or -1 if there isn't one. You could extract it by using the substr command, if you just wanted the variable name.

Upvotes: 0

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