[Rd] WISH: set.seed(seed) to produce error if length(seed) != 1 (now silent)
Henrik Bengtsson
henr|k@bengt@@on @end|ng |rom gm@||@com
Fri Sep 17 14:38:46 CEST 2021
> I’m curious, other than proper programming practice, why?
Life's too short for troubleshooting silent mistakes - mine or others.
While at it, searching the interwebs for use of set.seed(), gives
mistakes/misunderstandings like using set.seed(<double>), e.g.
> set.seed(6.1); sum(.Random.seed)
[1] 73930104
> set.seed(6.2); sum(.Random.seed)
[1] 73930104
which clearly is not what the user expected. There are also a few
cases of set.seed(<character>), e.g.
> set.seed("42"); sum(.Random.seed)
[1] -2119381568
> set.seed(42); sum(.Random.seed)
[1] -2119381568
which works just because as.numeric("42") is used.
/Henrik
On Fri, Sep 17, 2021 at 12:55 PM GILLIBERT, Andre
<Andre.Gillibert using chu-rouen.fr> wrote:
>
> Hello,
>
> A vector with a length >= 2 to set.seed would probably be a bug. An error message will help the user to fix his R code. The bug may be accidental or due to bad understanding of the set.seed function. For instance, a user may think that the whole state of the PRNG can be passed to set.seed.
>
> The "if" instruction, emits a warning when the condition has length >= 2, because it is often a bug. I would expect a warning or error with set.seed().
>
> Validating inputs and emitting errors early is a good practice.
>
> Just my 2 cents.
>
> Sincerely.
> Andre GILLIBERT
>
> -----Message d'origine-----
> De : R-devel [mailto:r-devel-bounces using r-project.org] De la part de Avraham Adler
> Envoyé : vendredi 17 septembre 2021 12:07
> À : Henrik Bengtsson
> Cc : R-devel
> Objet : Re: [Rd] WISH: set.seed(seed) to produce error if length(seed) != 1 (now silent)
>
> Hi, Henrik.
>
> I’m curious, other than proper programming practice, why?
>
> Avi
>
> On Fri, Sep 17, 2021 at 11:48 AM Henrik Bengtsson <
> henrik.bengtsson using gmail.com> wrote:
>
> > Hi,
> >
> > according to help("set.seed"), argument 'seed' to set.seed() should be:
> >
> > a single value, interpreted as an integer, or NULL (see ‘Details’).
> >
> > From code inspection (src/main/RNG.c) and testing, it turns out that
> > if you pass a 'seed' with length greater than one, it silently uses
> > seed[1], e.g.
> >
> > > set.seed(1); sum(.Random.seed)
> > [1] 4070365163
> > > set.seed(1:3); sum(.Random.seed)
> > [1] 4070365163
> > > set.seed(1:100); sum(.Random.seed)
> > [1] 4070365163
> >
> > I'd like to suggest that set.seed() produces an error if length(seed)
> > > 1. As a reference, for length(seed) == 0, we get:
> >
> > > set.seed(integer(0))
> > Error in set.seed(integer(0)) : supplied seed is not a valid integer
> >
> > /Henrik
> >
> > ______________________________________________
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> > https://stat.ethz.ch/mailman/listinfo/r-devel
> >
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