`as.IDate()` drops names

[DavisVaughan]

With data.table 1.16.2

library(data.table)

x <- c(a = "2019-01-01")
x
#>            a 
#> "2019-01-01"

as.IDate(x)
#> [1] "2019-01-01"

# data.table:::as.IDate.Date calls this
# as.integer() step loses names
as.integer(as.Date(x))
#> [1] 17897

^{Created on 2025-08-14 with reprex v2.1.1}

[DavisVaughan]

Another test case for you is this particularly confusing case - due to c.IDate calling as.IDate()

c(a = data.table::as.IDate("2019-01-01"))
#> [1] "2019-01-01"

^{Created on 2025-08-14 with reprex v2.1.1}

[MichaelChirico]

Thanks...

With data.table 1.16.2

Confirmed on a more recent version too.

Most importantly, this is not consistent with as.Date():

as.Date(x)
#            a 
# "2019-01-01" 

c(a = as.Date("2019-01-01"))
#            a 
# "2019-01-01" 

I do wish R would make up its mind on whether as.* retains names 🙃

Do you have a use case in mind to help set priority for a fix?

[DavisVaughan]

No rush on my end, I'm working on r-lib/vctrs#1961 and I noticed it when adding tests. I've got a little helper for tests that retains names, so no issues for me

[DavisVaughan]

I typically do take the stance that as.* should retain names because it (always?) retains length, and if you retain the length you can also map the names over.

[MichaelChirico]

I tend to agree but it's not quite so simple:

as.integer(matrix(1:2, ncol=2L, dimnames = list('a', c('b', 'c'))))
# [1] 1 2

[DavisVaughan]

I guess I have feelings about the shape of that return value too 😛

[ben-schwen]

I do wish R would make up its mind on whether as.* retains names 🙃

@MichaelChirico something we should bring up in the bug tracker? I understand that its not a pressing issue to the usual user but should be consistent at least.

[venom1204]

hi @joshhwuu , @MichaelChirico
i think one way is to capture the names of the input and restore them setattr(res,''names'',nm), i plan to apply this to as.idate.date,as.idate.numeric,as.idate.POSIXctand theas.itime.numericto ensure teh consistency across bothidateand theitime```.

if this sounds good i will be happy to proceed with the pr .