[R] Removing objects and clearing memory

[Rolf Turner]

On 13/04/11 09:49, Denis Kazakiewicz wrote:
> On 13.04.2011 00:39, Jim Silverton wrote:
>> How do I remove all objects except one in R?
>>
> rm(list=ls()) #will remove ALL objects

But he wanted to remove all objects ***except one***!!!  So what's the
point of this answer?

I can't see any way except a rather round-about kludge to do what the
OP wants.

Create a function:

rmabo <- function(x) {
# Remove all but one.
     fff <- tempfile()
     save(list=deparse(substitute(x)),file=fff)
     rm(list=ls(pos=1),pos=1)
     load(fff,envir=.GlobalEnv)
     unlink(fff)
}

Save this function (otherwise it will get removed when you remove
all objects except one, and rmabo is not the one, and will be lost):

save(rmabo,file=".rmabo.rda")

Whenever you want to remove all objects except one, attach the
data base in which you have saved "rmabo".  (You only need to do
the attaching once per session; if you like you could put the attach
command in your .Rprofile.)

attach(".rmabo.rda")

Then to remove all objects except "melvin" execute rmabo(melvin).
E.g.:

rm(list=ls)
ls()
character(0)
melvin <- clyde <- irving <- fred <- 42
ls()
[1] "clyde"  "fred"   "irving" "melvin"
rmabo(melvin)
ls()
[1] "melvin"

This seems to work.  Anyone have any cleverer ideas to accomplish the
stated objective?

     cheers,

         Rolf Turner