[Rd] as.Date(Inf) displays as 'NA' but is actually 'Inf'

[William Dunlap]

format.Date runs into trouble long before Inf:
  > as.Date("2018-03-05") + c(2147466052, 2147466053)
  [1] "5881580-07-11"  "-5877641-06-23"

Bill Dunlap
TIBCO Software
wdunlap tibco.com


On Tue, Mar 5, 2019 at 2:33 PM Gabriel Becker <gabembecker using gmail.com> wrote:

> Richard,
>
> Well others may chime in here, but from a mathematical point of view, the
> concept of "infinite days from right now" is well-defined, so it maybe a
> "valid" date in that sense, but what day and month it will be (year will be
> Inf) are indeterminate/not well defined. Those are rightfully, NA, it
> seems?
>
> I mean you could disallow dates to take Inf at all, ever. I don't feel
> strongly one way or the other about that, personally. That said, if inf
> dates are allowed, its not clear to me that displaying the "Formatted" date
> string as NA, even if the value isn't,  is wrong given it can't be
> determined for that "date" is. It could be displayed differently, I
> suppose, but all the ones I can think of off the top of my head would be
> problematic and probably break lots of formatted-dates parsing code out
> there in the wild (and in R, I would guess). Things like displaying
> "Inf-NA-NA", or just "Inf". Neither of those are going to handle a
> read-write round-trip well, I think.
>
> So my personal don't-really-have-a-hat-in-the-ring opinion would be to
> either leave it as is, or force as.Date(Inf, bla) to actually be NA.
>
> Best,
> ~G
>
> On Tue, Mar 5, 2019 at 12:06 PM Richard White <w using rwhite.no> wrote:
>
> > Hi,
> >
> > I think I've discovered a bug in base R.
> >
> > Basically, when using 'Inf' as as 'Date', is is visually displayed as
> > 'NA', but R still treats it as 'Inf'. So it is very confusing to work
> > with, and can easily lead to errors:
> >
> > # Visually displays as NA
> >  > as.Date(Inf, origin="2018-01-01")
> > [1] NA
> >
> > # Visually displays as NA
> >  > str(as.Date(Inf, origin="2018-01-01"))
> > Date[1:1], format: NA
> >
> > # Is NOT NA
> >  > is.na(as.Date(Inf, origin="2018-01-01"))
> > [1] FALSE
> >
> > # Is still Inf
> >  > is.infinite(as.Date(Inf, origin="2018-01-01"))
> > [1] TRUE
> >
> > This gets really problematic when you are collapsing dates over groups
> > and you want to find the first date of a group. Because min() returns
> > Inf if there is no data:
> >
> > # Visually displays as NA
> >  > as.Date(min(), origin="2018-01-01")
> > [1] NA
> > Warning message: In min() : no non-missing arguments to min; returning
> Inf
> >
> > # Visually displays as NA
> >  > str(as.Date(min(), origin="2018-01-01"))
> > Date[1:1], format: NA
> > Warning message: In min() : no non-missing arguments to min; returning
> Inf
> >
> > # Is not NA
> >  > is.na(as.Date(min(), origin="2018-01-01"))
> > [1] FALSE
> > Warning message: In min() : no non-missing arguments to min; returning
> Inf
> >
> > # This is bad!
> >  > as.Date(min(), origin="2018-01-01") > "2018-01-01"
> > [1] TRUE
> > Warning message: In min() : no non-missing arguments to min; returning
> Inf
> >
> > Here is my sessionInfo():
> >
> >  > sessionInfo()
> > R version 3.5.0 (2018-04-23)
> > Platform: x86_64-pc-linux-gnu (64-bit)
> > Running under: Debian GNU/Linux 9 (stretch)
> > Matrix products: default
> > BLAS: /usr/lib/openblas-base/libblas.so.3
> > LAPACK: /usr/lib/libopenblasp-r0.2.19.so
> >
> > locale:
> > [1] LC_CTYPE=C.UTF-8 LC_NUMERIC=C LC_TIME=C.UTF-8 LC_COLLATE=C.UTF-8
> > LC_MONETARY=C.UTF-8
> > [6] LC_MESSAGES=C LC_PAPER=C.UTF-8 LC_NAME=C LC_ADDRESS=C LC_TELEPHONE=C
> > [11] LC_MEASUREMENT=C.UTF-8 LC_IDENTIFICATION=C
> >
> > attached base packages:
> > [1] stats graphics grDevices utils datasets methods base loaded via a
> > namespace (and not attached):
> > [1] compiler_3.5.0 tools_3.5.0 yaml_2.1.19
> >
> >  > Sys.getlocale()
> > [1]
> >
> >
> "LC_CTYPE=C.UTF-8;LC_NUMERIC=C;LC_TIME=C.UTF-8;LC_COLLATE=C.UTF-8;LC_MONETARY=C.UTF-8;LC_MESSAGES=C;LC_PAPER=C.UTF-8;LC_NAME=C;LC_ADDRESS=C;LC_TELEPHONE=C;LC_MEASUREMENT=C.UTF-8;LC_IDENTIFICATION=C"
> >
> > ______________________________________________
> > R-devel using r-project.org mailing list
> > https://stat.ethz.ch/mailman/listinfo/r-devel
> >
>
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