Preserve state of random number generator in .onAttach()

[TimTaylor]

Please place an "x" in all the boxes that apply

• [ ] I have the most recent version of poppr and R
• [x] I have found a bug
  • [ ] I have searched for solutions on this site and the poppr forum
  • [ ] I have a reproducible example
• [x] I want to request a new feature

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Currently .onAttach() will change the state of a users random number generator.

https://github.com/grunwaldlab/poppr/blob/2ae5741bb73b4034993dc6c58ec264c379fbd6f5/R/zzz.r#L57

Not a bug per se but would you consider a change to preserve it?

For reference I believe {ggplot2} was updated to use withr::with_preserve_seed() for this reason.

Motivate by this thread https://fosstodon.org/@henrikbengtsson@mastodon.social/112079393660379008

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[zkamvar]

Thank you for opening this, Tim. I think a change should definitely happen. I'll probably use Ben's millisecond trick to avoid calling the rng all together.

[zkamvar]

Alas, the RNG is still modified, which means that one of the packages being loaded is modifying it. I tried debugging for set.seed(), but that gave me shiny, which should safely modify its own internal seed.

[zkamvar]

Actually, shiny might be the culprit here.

exists(".Random.seed")
#> [1] FALSE
library(shiny)
exists(".Random.seed")
#> [1] TRUE

^{Created on 2024-03-13 with reprex v2.0.2}

[TimTaylor]

@zkamvar interesting 🤔. Away from pc to take a proper look but seems like they've tried to handle this but it's not quite working. Will have a proper gander when I get a moment.

[TimTaylor]

@zkamvar - Actually I think it's ok. In a vanilla session there is no seed to preserve.

$ R -s -e "runif(1); withr::with_preserve_seed(runif(1)); library(shiny); runif(1)"
[1] 0.455732
[1] 0.5350188
[1] 0.5350188

but even without shiny, you cannot preserve a seed that doesn't exist

$ R -s -e "exists('.Random.seed'); withr::with_preserve_seed(runif(1)); runif(1); exists('.Random.seed')"
[1] FALSE
[1] 0.2837904
[1] 0.02483963
[1] TRUE

So I think shiny is ok. Does that make sense?

[zkamvar]

Ah yeah that does make sense! Thank you!