I'd say a more serious problem would be using set.seed(.Random.seed),
because the first entry codes for RNGkind, it hardly varies at all. So
this sequence could really mislead someone:
> set.seed(.Random.seed)
> sum(.Random.seed)
[1] 24428993419
# Use it to get a new .Random.seed value:
> runif(1)
[1] 0.3842704
> sum(.Random.seed)
[1] -13435151647
# So let's make things really random, by using the new seed as a seed:
> set.seed(.Random.seed)
> sum(.Random.seed)
[1] 24428993419
# Back to the original!
Duncan Murdoch
On 17/09/2021 8:38 a.m., Henrik Bengtsson wrote:
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.gillib...@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-boun...@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.bengts...@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
______________________________________________
R-devel@r-project.org mailing list
https://stat.ethz.ch/mailman/listinfo/r-devel
--
Sent from Gmail Mobile
[[alternative HTML version deleted]]
______________________________________________
R-devel@r-project.org mailing list
https://stat.ethz.ch/mailman/listinfo/r-devel
______________________________________________
R-devel@r-project.org mailing list
https://stat.ethz.ch/mailman/listinfo/r-devel
______________________________________________
R-devel@r-project.org mailing list
https://stat.ethz.ch/mailman/listinfo/r-devel
