[R] How can certain variables be automatically excluded from being saved?

[Ralf Goertz]

Am Thu, 1 Apr 2021 08:39:45 -0400
schrieb Duncan Murdoch <murdoch.duncan using gmail.com>:

> On 01/04/2021 4:05 a.m., Ralf Goertz wrote:
> > Hi,
> >
> > after having read here about the "seed problem" I wonder if there
> > is a way to automatically exclude certain variables from being
> > saved when the workspace image is saved at the end of an
> > interactive session. I have been using .First() and .Last() for
> > ages but apparently they are of no help as .First() gets called
> > before loading the workspace and .Last() after it has been saved.
> > At least the line
> >
> > if (".Random.seed" %in% ls(all.names=T)) rm(.Random.seed, pos=1)
> >
> > in either of those functions doesn't have the desired effect.
>
> Jim suggested a way to do that, but I don't think it's really a good
> idea:  it just fixes one aspect of the problem, it doesn't solve the
> whole thing.
>
> The real problem is saving the workspace occasionally, but always
> loading it.  The "always loading" part is automatic, so I think the
> real solution should address the "occasionally saving" part.

Yes, that is exactly what I quite often do. I have to work in different
projects and I usually start R in the project directory. When I do
serious stuff I save afterwards. But quite often I want to check
something quickly and then I don't want to clutter up my workspace.

> If you always save the workspace, things are fine.  You'll save the
> seed at the end of one session, and load it at the beginning of the
> next.
>
> If you never save the workspace, things are also fine.  You'll always
> generate a new seed in each session that needs one.
>
> Personally, I believe in the "never save it" workflow.  I think it
> has lots of benefits besides the random seed issue:  you won't get a
> more-and-more cluttered workspace over time, you end up with more
> reproducible results, etc.  However, I can understand that some
> people use a different workflow, so "always save it" is sometimes a
> reasonable choice.
>
> So the real problem is the "sometimes save it" workflow, which is
> **encouraged** by the default q(save = "default") option, which asks
> when interactive.  Changing the default to act like q(save = "no")
> would be my preference (and that's how I configure things), but
> changing it to act like q(save = "yes") would be an improvement over
> the current choice.

I would prefer to be able to only save the history since that is where
the work is done. Usually, my data is easily restored using commands
from the history. I could probably accomplish that by linking .RData to
/dev/null or making it an empty readonly file. However, I would have to
do that in every directory I happen to use R in.