Hi Martyn,
Thanks for finding that stuff in the documentation, and apologies for
not reading the whole thing carefully. I guess when I got to the
minutiae about printing years before '999', I started to skim.
My vote is for more sensible / standard behavior, but I guess this has
probably been this way for a long time.
Frederick
On Tue, Jan 17, 2017 at 01:35:35PM +0000, Martyn Plummer wrote:
> Hi Frederik,
>
> On Mon, 2017-01-16 at 18:20 -0800, frede...@ofb.net wrote:
> > Hi R Devel,
> >
> > I wrote some code which depends on 'strptime' being able to parse an
> > incomplete date, like this:
> >
> > >
> > > base::strptime("2016","%Y")
> > [1] "2016-01-14 PST"
> >
> > The above works - although it's odd that it gives the month and day
> > for Sys.time(). I might expect it to set them both to zero as the GNU
> > libc strptime does on my system, or to use January 1 which would also
> > be reasonable.
>
> From the help page for strptime:
>
> "For ‘strptime’ the input string need not specify the date completely:
> it is assumed that unspecified seconds, minutes or hours are zero, and
> an unspecified year, month or day is the current one."
>
> > When I specify the month, however, I get NA:
> >
> > >
> > > base::strptime("2016-12","%Y-%m")
> > [1] NA
> > >
> > > base::strptime("1", "%m")
> > [1] NA
> >
> > Any reason for this to be the case?
>
> Also from the help page:
>
> "(However, if a month is specified, the day of that month has to be
> specified by ‘%d’ or ‘%e’ since the current day of the month need not
> be valid for the specified month.)"
>
> If strptime("2016-2", "%Y-%m") just filled in the current day then it
> would give valid output when called on the 1st to the 28th of each
> month, but would give either invalid output or fail when called on the
> 29th to the 31st of any month. This would be a nightmare to debug. The
> current behaviour lets you know there is a logical problem with your
> input.
>
> > I reported a bug here:
> >
> > https://bugs.r-project.org/bugzilla3/show_bug.cgi?id=17212
> >
> > but I don't think I'm getting emails from Bugzilla so maybe best to
> > ping me if anyone replies there instead.
>
> See the general guidance on submitting bug reports:
>
> "Code doing something unexpected is not necessarily a bug - make sure to
> carefully review the documentation for the function you are calling to see if
> the behaviour it exhibits is what it was designed to do, even if it’s not
> what you want."
>
> https://www.r-project.org/bugs.html
>
>
> Martyn
>
> > I've just written a simple reimplementation of 'strptime' for my own
> > use; I hope this bug report may be useful to others.
> >
> > Thank you,
> >
> > Frederick
> >
> > ______________________________________________
> > R-devel@r-project.org mailing list
> > https://stat.ethz.ch/mailman/listinfo/r-devel
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