Re: [Rd] Saving nothing with save()

From: Martin Maechler <maechler_at_stat.math.ethz.ch>
Date: Mon, 19 Dec 2011 12:39:39 +0100

>>>>> Barry Rowlingson <b.rowlingson_at_lancaster.ac.uk> >>>>> on Sun, 18 Dec 2011 01:32:52 +0000 writes:

> Scenario: Here I am working away in R. I've got results
> that prove global warming is anthropogenic and also the
> solution for producing limitless carbon-neutral energy
> from nuclear fusion. Its been a good day.

> So, I want to save my work. I don't want to overwrite my
> current .RData, so I save it to another file:

> save(file="prize.RData") # just need to email this to the
> Nobel committee q() Save workspace image? [y/n/c]: - "no"
> I don't want to save the workspace image, I just saved
> everything to "prize.RData". But gee, it did seem to do
> that quite quickly considering the volume of evidential
> data in my work. My unix shell prompt returns.

> Uh oh. See what I did there? I typed 'save' when I meant
> 'save.image'. What does that give me?

> A 42 byte, empty, latest.RData, and because there was no
> warning or error I quit without saving it
> again. Oops. Massive Data Loss.

> Is there any reason why save(file="file.RData") couldn't
> warn or error if you try and save nothing? There's no
> obvious check in the R code for save.

> Barry

> PS the above scenario is fictional.
really? ;-)

well, after *not* save()ing all your findings, it wouldn't have been such a good day, would it?

well, in spite of that.
I agree that save() should warn or stop in that case. I have now committed a version -- to R-devel only -- which stop()s if 'pretest=TRUE' and uses warning() otherwise, name="0485qlink2"><a name="0485qlink2">e.g., in the case of save.image() when there's nothing to save.

Thank you, Barry. for the suggestion!
Martin

> When did I last have a good day?

(I wish you more of those..)



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