R 4.0 dependency (stringsAsFactors)

[MichaelChirico]

The stated R dependency is quite old:

sl3/DESCRIPTION

Line 32 in 2bc71d8

Depends: R (>= 2.14.0)

But this code relies on the default behavior of as.data.frame()'s stringsAsFactors = FALSE in R 4.0 and later:

sl3/R/sl3_Task.R

Line 177 in 2bc71d8

Xint <- as.list(as.data.frame(t(expand.grid(Xmatch))))

[nhejazi]

Thanks for bringing this up, it's a good find. I wasn't aware of changes to as.data.frame()'s default behavior, but it looks like as.data.table() has a stringsAsFactors argument that defaults to FALSE, and the data.table package is backwards compatible with R 3.1.0+, so I think it will suffice to update the minimum R version of sl3 to match with that used by data.table (although in practice other dependencies will determine the limit) and to switch out that particular use of as.data.frame() with as.data.table(). I'll do that in a PR shortly.

[MichaelChirico]

yep, that'll work. thanks!

[nhejazi]

resolved by #378