[Rd] seq.Date bug?

[Jeffrey Ryan]

format(ISOdate(2012,1:12,1),"%b-%Y")

[1] "Jan-2012" "Feb-2012" "Mar-2012" "Apr-2012" "May-2012" "Jun-2012"
[7] "Jul-2012" "Aug-2012" "Sep-2012" "Oct-2012" "Nov-2012" "Dec-2012"

First of the month is just as clean, and AFAIR they all have a first ;-)

Jeff

On Tue, Jan 31, 2012 at 2:37 PM, Dirk Eddelbuettel <edd at debian.org> wrote:
>
> On 31 January 2012 at 15:17, Duncan Murdoch wrote:
> | On 12-01-31 2:56 PM, Dirk Eddelbuettel wrote:
> | >
> | > R>  seq(as.Date(Sys.Date()), by="-1 months", length=6)
> | > [1] "2012-01-31" "2011-12-31" "2011-12-01" "2011-10-31" "2011-10-01" "2011-08-31"
> | > R>
> | >
> | > Notice how October appears twice.
> |
> | >
> | > Now, date arithmetic is gruesome but the documentation for seq.Date et al
> | > does not hint it wouldn't honour the by= argument.  So a bug, or merely a
> | > somewhat less than desirable features.
> |
> | It is giving you Jan 31, Dec 31, Nov 31, Oct 31, Sep 31, Aug 31 --
> | except some of those months don't have 31 days, so it is converting
> | those dates to ones that really exist.  (This is documented in ?seq.POSIXt.)
> |
> | Isn't this what you asked for?
>
> No as I was feeding this into format(..., "%b-%y") to create 'pretty' names,
> and the double entries screw that.
>
> Morale:  pick a mid-month date, and shift that.
>
> Dirk
>
> | Duncan Murdoch
> |
> |
> | >
> | > (And yes, I think I know that Hadley's lubridate has code for this too, but
> | > so may my RcppBDT which is sitting on top of Boost::DateTime code ...)
> | >
> | > Dirk
> | >
> |
>
> --
> "Outside of a dog, a book is a man's best friend. Inside of a dog, it is too
> dark to read." -- Groucho Marx
>
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-- 
Jeffrey Ryan
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