Question

This is one of those “there has to be a function for this” questions. It’s not that big a deal, but it’s just annoying enough that every time I rename an object I wonder if there’s a better way.

Suppose I capitalize an object that I’ve created and realize I’d rather have it uncapitalized:

# Create test data
X <- runif(100)
# Rename the object
x <- X
rm(X)

Is there a one-command way of doing this (that also avoids the re-copy for memory/speed reasons)? There are a few commands named rename in various packages but they all work on elements within a list, rather than on the list (or other object) itself.

Answer 1

I don’t know of a built in way to do this but you could easily write your own function to do something along these lines. For instance this does just that without any checking to make sure the object exists or whether or not there is already an object named what you want to rename to.

mv <- function(x, y){
    x_name <- deparse(substitute(x))
    y_name <- deparse(substitute(y))

    assign(y_name, x, pos = 1)
    rm(list = x_name, pos = 1)
    invisible()
}

Some example use

> x <- 3
> x
[1] 3
> y
Error: object 'y' not found
> mv(x, y)
> x
Error: object 'x' not found
> y
[1] 3

---

Edit: For those that didn’t follow the link in the comments here is a version written by Rolf Turner that does some checking to make sure the object we want to move actually exists and asks us if we want to overwrite an existing object if the new name already has an object in it.

mv <- function (a, b) {
    anm <- deparse(substitute(a))
    bnm <- deparse(substitute(b))
    if (!exists(anm,where=1,inherits=FALSE))
        stop(paste(anm, "does not exist.\n"))
    if (exists(bnm,where=1,inherits=FALSE)) {
        ans <- readline(paste("Overwrite ", bnm, "? (y/n) ", sep = ""))
        if (ans != "y")
            return(invisible())
    }
    assign(bnm, a, pos = 1)
    rm(list = anm, pos = 1)
    invisible()
}