[Rd] seq.Date bug?
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. (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 __ R-devel@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-devel
Re: [Rd] seq.Date bug?
I was prompted to try it myself: On Tue, Jan 31, 2012 at 2:56 PM, Dirk Eddelbuettel e...@debian.org 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. As does December. 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. The by argument chokes on month if the current day is greater than the shortest month in the sequence (presumably due to the irregular nature of month lengths): For leap year 2012: seq(as.Date(2012/1/29), by=month, length.out=12) # works [1] 2012-01-29 2012-02-29 2012-03-29 2012-04-29 2012-05-29 [6] 2012-06-29 2012-07-29 2012-08-29 2012-09-29 2012-10-29 [11] 2012-11-29 2012-12-29 seq(as.Date(2012/1/30), by=month, length.out=12) # fails [1] 2012-01-30 2012-03-01 2012-03-30 2012-04-30 2012-05-30 [6] 2012-06-30 2012-07-30 2012-08-30 2012-09-30 2012-10-30 [11] 2012-11-30 2012-12-30 While for non-leap year 2011: seq(as.Date(2011/1/28), by=month, length.out=12) # works [1] 2011-01-28 2011-02-28 2011-03-28 2011-04-28 2011-05-28 [6] 2011-06-28 2011-07-28 2011-08-28 2011-09-28 2011-10-28 [11] 2011-11-28 2011-12-28 seq(as.Date(2011/1/29), by=month, length.out=12) #fails [1] 2011-01-29 2011-03-01 2011-03-29 2011-04-29 2011-05-29 [6] 2011-06-29 2011-07-29 2011-08-29 2011-09-29 2011-10-29 [11] 2011-11-29 2011-12-29 sessionInfo() R version 2.14.1 (2011-12-22) Platform: x86_64-redhat-linux-gnu (64-bit) locale: [1] LC_CTYPE=en_US.UTF-8 LC_NUMERIC=C [3] LC_TIME=en_US.UTF-8LC_COLLATE=en_US.UTF-8 [5] LC_MONETARY=en_US.UTF-8LC_MESSAGES=en_US.UTF-8 [7] LC_PAPER=C LC_NAME=C [9] LC_ADDRESS=C LC_TELEPHONE=C [11] LC_MEASUREMENT=en_US.UTF-8 LC_IDENTIFICATION=C attached base packages: [1] stats graphics grDevices utils datasets methods base loaded via a namespace (and not attached): [1] tools_2.14.1 -- Sarah Goslee http://www.functionaldiversity.org __ R-devel@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-devel
Re: [Rd] seq.Date bug?
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 __ R-devel@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-devel
Re: [Rd] seq.Date bug?
On Jan 31, 2012, at 2:07 PM, Sarah Goslee wrote: I was prompted to try it myself: On Tue, Jan 31, 2012 at 2:56 PM, Dirk Eddelbuettel e...@debian.org 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. As does December. 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. The by argument chokes on month if the current day is greater than the shortest month in the sequence (presumably due to the irregular nature of month lengths): For leap year 2012: seq(as.Date(2012/1/29), by=month, length.out=12) # works [1] 2012-01-29 2012-02-29 2012-03-29 2012-04-29 2012-05-29 [6] 2012-06-29 2012-07-29 2012-08-29 2012-09-29 2012-10-29 [11] 2012-11-29 2012-12-29 seq(as.Date(2012/1/30), by=month, length.out=12) # fails [1] 2012-01-30 2012-03-01 2012-03-30 2012-04-30 2012-05-30 [6] 2012-06-30 2012-07-30 2012-08-30 2012-09-30 2012-10-30 [11] 2012-11-30 2012-12-30 While for non-leap year 2011: seq(as.Date(2011/1/28), by=month, length.out=12) # works [1] 2011-01-28 2011-02-28 2011-03-28 2011-04-28 2011-05-28 [6] 2011-06-28 2011-07-28 2011-08-28 2011-09-28 2011-10-28 [11] 2011-11-28 2011-12-28 seq(as.Date(2011/1/29), by=month, length.out=12) #fails [1] 2011-01-29 2011-03-01 2011-03-29 2011-04-29 2011-05-29 [6] 2011-06-29 2011-07-29 2011-08-29 2011-09-29 2011-10-29 [11] 2011-11-29 2011-12-29 The issue is the if the next month in sequence does not contain the date, then the date is advanced until the next valid date. For example: seq.Date(as.Date(2012/01/30), by = month, length.out = 3) [1] 2012-01-30 2012-03-01 2012-03-30 February 30th does not exist, thus that date is advanced to March 1st, then the next date in the sequence is March 30th. Thus, two days in March. seq.Date(as.Date(2012/10/31), by = month, length.out = 3) [1] 2012-10-31 2012-12-01 2012-12-31 Here, November 31st does not exist, so the date is advanced to the next valid date, December 1 and then the next date is December 31. Thus, two days in December. So it appears to be working correctly. HTH, Marc Schwartz __ R-devel@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-devel
Re: [Rd] seq.Date bug?
As Duncan pointed out, this is documented in ?seq.POSIXt: Using ‘month’ first advances the month without changing the day: if this results in an invalid day of the month, it is counted forward into the next month: see the examples. But ?seq.Date gives the impression that the construct Dirk and I tried should work: ## find all 7th of the month between two dates, the last being a 7th. st - as.Date(1998-12-17) en - as.Date(2000-1-7) ll - seq(en, st, by=-1 month) rev(ll[ll st ll en]) is given as an example, and it is not pointed out that this won't work for the 30th of the month. Normally one can extrapolate from patterns given in the examples, and here that isn't true. So perhaps the help should be modified slightly instead? Sarah -- Sarah Goslee http://www.sarahgoslee.com __ R-devel@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-devel
Re: [Rd] seq.Date bug?
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 __ R-devel@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-devel
Re: [Rd] seq.Date bug?
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 e...@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 __ R-devel@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-devel -- Jeffrey Ryan jeffrey.r...@lemnica.com www.lemnica.com www.esotericR.com R/Finance 2012: Applied Finance with R www.RinFinance.com See you in Chicago __ R-devel@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-devel
Re: [Rd] seq.Date bug?
On 31 January 2012 at 15:28, Sarah Goslee wrote: | As Duncan pointed out, this is documented in ?seq.POSIXt: | | Using ‘month’ first advances the month without changing the day: | if this results in an invalid day of the month, it is counted | forward into the next month: see the examples. | | But ?seq.Date gives the impression that the construct Dirk and I tried | should work: | | ## find all 7th of the month between two dates, the last being a 7th. | st - as.Date(1998-12-17) | en - as.Date(2000-1-7) | ll - seq(en, st, by=-1 month) | rev(ll[ll st ll en]) | | is given as an example, and it is not pointed out that this won't work for | the 30th of the month. Normally one can extrapolate from patterns given | in the examples, and here that isn't true. So perhaps the help should | be modified slightly instead? Yup, that would indeed help with this infelicity. 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 __ R-devel@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-devel
Re: [Rd] seq.Date bug?
-Original Message- From: r-devel-boun...@r-project.org [mailto:r-devel-boun...@r-project.org] On Behalf Of Jeffrey Ryan Sent: January-31-12 12:47 PM To: Dirk Eddelbuettel Cc: R-devel org Subject: Re: [Rd] seq.Date bug? 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 ;-) From which you can get the last... format(ISOdate(2012,1:12,1)-86400,%d-%b-%Y) [1] 31-Dec-2011 31-Jan-2012 29-Feb-2012 31-Mar-2012 30-Apr-2012 31-May-2012 [7] 30-Jun-2012 31-Jul-2012 31-Aug-2012 30-Sep-2012 31-Oct-2012 30-Nov-2012 ... though leap seconds might require a bit more tweaking... Steven McKinney Statistician Molecular Oncology and Breast Cancer Program British Columbia Cancer Research Centre Jeff On Tue, Jan 31, 2012 at 2:37 PM, Dirk Eddelbuettel e...@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 __ R-devel@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-devel -- Jeffrey Ryan jeffrey.r...@lemnica.com www.lemnica.com www.esotericR.com R/Finance 2012: Applied Finance with R www.RinFinance.com See you in Chicago __ R-devel@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-devel __ R-devel@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-devel
