R help - Mar 2012 - rm(list=ls())

R-2.14.2, Win7 x64

Dear list,

I have the habit of including rm(list=ls()) at the top of most of my 
scripts. However, I wonder whether rm(list=ls()) gives the exact same 
result as closing R and starting again fresh.
In other words, is it possible that there will be differences on how a 
script runs under a fresh start of R versus when I "only" use 
rm(list=ls()) , or should both approaches give the exact same starting 
situation every time?

Thanks,
Peter

No, it won't give the same result. If you load packages or have hidden
variables / environments, they'll remain in the session or if you
change global options they'll stay. It's a somewhat frequently asked
question, but there's no way to get a "factory fresh" session
without
restarting R. You can get pretty close though with

#####################################
####### rm(list = ls(all.names = TRUE)) # will get hidden (.xyz) variables
#####################################

and detach() applied to all of the package namespaces. You'll still
have some registered methods and whatnot around, but this will do most
of the cleanup.

Michael


On Mon, Mar 5, 2012 at 6:29 PM, Wet Bell Diver <wetbelldiver at gmail.com>
wrote:
> R-2.14.2, Win7 x64
>
> Dear list,
>
> I have the habit of including rm(list=ls()) at the top of most of my
> scripts. However, I wonder whether rm(list=ls()) gives the exact same
result
> as closing R and starting again fresh.
> In other words, is it possible that there will be differences on how a
> script runs under a fresh start of R versus when I "only" use
rm(list=ls())
> , or should both approaches give the exact same starting situation every
> time?
>
> Thanks,
> Peter
>
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