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? 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
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