How to convert variable (object) name into String

Question

I have the following data frame with variable name "foo";

 > foo <-c(3,4);

What I want to do is to convert "foo" into a string. So that in a function I don't have to recreate another extra variables:

   output <- myfunc(foo)
   myfunc <- function(v1) {
     # do something with v1
     # so that it prints "FOO" when 
     # this function is called 
     #
     # instead of the values (3,4)
     return ()
   }

Solution

You can use deparse and substitute to get the name of a function argument:

myfunc <- function(v1) {
  deparse(substitute(v1))
}

myfunc(foo)
[1] "foo"

Comments

[Mahdi Jadaliha]

+1. Thanks for the helpful answer, what about if I pass foo[1]; is there a way to get just "foo" back?

[Sven Hohenstein]

@MahdiJadaliha You can try this function: myfunc <- function(v1) { s <- substitute(v1); if (length(s) == 1) deparse(s) else sub("\\(.", "", s[2]) }.

[theforestecologist]

How would you do this with multiple objects? Specifically, how would you do it in a way to get separate strings for each object name? (For example, if I had object foo, foo1, and foo2 and I wanted to create a list of their names as separate character strings).

[Sven Hohenstein]

@theforestecologist If the function has multiple parameters, you can use deparse(substitute(.)) for each parameter, store the result in a variable, and put the variables in a list afterwards.

[SumNeuron]

@SvenHohenstein this doesn't work when you use a for loop...

[cloudscomputes]

you can also use deparse(quote(var)) in which quote freeze the var from evaluation and deparse which is the inverse of parse make the symbol back to string

[Salix]

@theforestecologist the best I've found is : unlist(strsplit(gsub("^.*\\(|\\)|\\s","", deparse(substitute(x))), ","))

[Salix]

actually see : this and that