How to get the object name as a string inside a function in r

I want to change column names of a data frame with a function.

To overwrite my data frame with the new column names, I used assign(), which first argument has to be the name of the same data frame as a string. To get the name as a string, I used deparse(substitute(x)), which worked outside the function. But inside the function, it returns the content of my data frame as a string instead of the name itself…

df <- data.frame(
  emp_id = c (1:5), 
  emp_name = c("Rick","Dan","Michelle","Ryan","Gary"),
  stringsAsFactors = FALSE
)

deparse(substitute(df))

rename_fun <- function(x) {
  colnames(x)[1] <- "___0"
  colnames(x)[2] <- "___1"

  y <- deparse(substitute(x))
  
    assign(y, x, envir = .GlobalEnv)      
}

rename_fun(df)

I also tried

as.character(substitute(x))

but the same problem…

Thanks for any help!

>Solution :

We need to use deparse/substitute at the start of the function

rename_fun <- function(x) {
 y <- deparse(substitute(x))
  colnames(x)[1] <- "___0"
  colnames(x)[2] <- "___1" 
  
  assign(y, x, envir = .GlobalEnv)      
}

-testing

> rename_fun(df)
> df
  ___0     ___1
1    1     Rick
2    2      Dan
3    3 Michelle
4    4     Ryan
5    5     Gary