Date class shows Inf as NA; this confuses the use of is.na()
Emil et al.,
On Mon, Jun 11, 2018 at 1:08 AM, Emil Bode <emil.bode at dans.knaw.nl> wrote:
I don't think there's much wrong with is.na(as_date(Inf,
origin='1970-01-01'))==FALSE, as there still is some "non-NA-ness" about
the value (as difftime shows), but that the output when printing is
confusing. The way cat is treating it is clearer: it does print Inf.
So would this be a solution?
format.Date <- function (x, ...)
{
xx <- format(as.POSIXlt(x), ...)
names(xx) <- names(x)
xx[is.na(xx) & !is.na(x)] <- paste('Invalid date:',as.numeric(x[is.na(xx)
& !is.na(x)]))
xx
}
Which causes this behaviour, which I think is clearer:
environment(print.Date) <- .GlobalEnv
x <- as_date(Inf, origin='1970-01-01')
print(x)
# [1] "Invalid date: Inf"
In my opinion, it's either invalid or it isn't. If it's actually invalid, as_date (and the equivalent core function which is actually relevant on this list) should fail; because it's an invalid date. If it *isn't* invalid, having the print method tell users it is seems problematic. And I think people seem to be leaning towards it not being invalid. A bit surprising to me, as my personal first thought was that infinite dates don't make any sense, but I don't really have a horse in this race and so defer to the cooler heads that are saying having an infinite date perhaps should not be disallowed explicitly. If it's not, though, it's not invalid and we shouldn't confuse users by saying it is, imho. Best, ~G
Best regards, Emil Bode Data-analyst +31 6 43 83 89 33 emil.bode at dans.knaw.nl DANS: Netherlands Institute for Permanent Access to Digital Research Resources Anna van Saksenlaan 51 | 2593 HW Den Haag | +31 70 349 44 50 | info at dans.knaw.nl <mailto:info at dans.kn> | dans.knaw.nl <applewebdata://71F677F0-6872-45F3-A6C4-4972BF87185B/www.dans.knaw.nl> DANS is an institute of the Dutch Academy KNAW <http://knaw.nl/nl> and funding organisation NWO <http://www.nwo.nl/>. Who will be the winner of the Dutch Data Prize 2018? Go to researchdata.nl to nominate. ?On 09/06/2018, 13:52, "R-devel on behalf of Joris Meys" < r-devel-bounces at r-project.org on behalf of jorismeys at gmail.com> wrote: And now I've seen I copied the wrong part of ?is.na
> The default method for is.na applied to an atomic vector returns a
logical vector of the same length as its argument x, containing TRUE
for
those elements marked NA or, for numeric or complex vectors, NaN, and
FALSE
otherwise.
Key point being "atomic vector" here.
On Sat, Jun 9, 2018 at 1:41 PM, Joris Meys <jorismeys at gmail.com>
wrote:
> Hi Werner,
>
> on ?is.na it says:
>
> > The default method for anyNA handles atomic vectors without a
class and
> NULL.
>
> I hear you, and it is confusing to say the least. Looking deeper, the
> culprit seems to be in the conversion of a Date to POSIXlt prior to
the
> formatting:
>
> > x <- as.Date(Inf,origin = '1970-01-01')
> > is.na(as.POSIXlt(x))
> [1] TRUE
>
> Given this implicit conversion, I'd argue that as.Date should really
> return NA as well when passed an infinite value. The other option is
to
> provide an is.na method for the Date class, which is -given is.na
is an
> internal generic- rather trivial:
>
> > is.na.Date <- function(x) is.na(as.POSIXlt(x))
> > is.na(x)
> [1] TRUE
>
> This might be a workaround for your current problem without needing
> changes to R itself. But this will give a "wrong" answer in the
sense that
> this still works:
>
> > Sys.Date() - x
> Time difference of -Inf days
>
> I personally would go for NA as the "correct" date for an infinite
value,
> but given that this will have implications in other areas, there is a
> possibility of breaking code and it should be investigated a bit
further
> imho.
> Cheers
> Joris
>
>
>
>
> On Fri, Jun 8, 2018 at 11:21 PM, Werner Grundlingh <
wgrundlingh at gmail.com>
> wrote:
>
>> Indeed. as_date is from lubridate, but the same holds for as.Date.
>>
>> The output and it's interpretation should be consistent, otherwise
it
>> leads
>> to confusion when programming. I understand that the difference
exists
>> after asking a question on Stack Overflow:
>> https://stackoverflow.com/q/50766089/914686
>> This understanding is never mentioned in the documentation - that
an Inf
>> date is actually represented as NA:
>> https://www.rdocumentation.org/packages/base/versions/3.5.0/
>> topics/as.Date
>> So I'm of the impression that the display should be fixed as a first
>> option
>> (thereby providing clarity/transparency in terms of back-end and
output),
>> or the documentation amended (to highlight this) as a second option.
>>
>> [[alternative HTML version deleted]]
>>
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>>
>
>
>
> --
> Joris Meys
> Statistical consultant
>
> Department of Data Analysis and Mathematical Modelling
> Ghent University
> Coupure Links 653, B-9000 Gent (Belgium)
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--
Joris Meys
Statistical consultant
Department of Data Analysis and Mathematical Modelling
Ghent University
Coupure Links 653, B-9000 Gent (Belgium)
<https://maps.google.com/?q=Coupure+links+653,%C2%A0B-
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