> On Jan 13, 2017, at 3:20 AM, Janko Thyson <janko.thy...@gmail.com> wrote: > > Hi David, > > thanks for replying and sorry about the HTML/non-plain-text email (I > forgot to change that, shouldn't have happened). > > Might just be me, but reading "The documentation for R datetime format > parameters ?strptime says %V is ignored on input." in the > documentation doesn't really tell me all that much. As a user, I would > read that, not completely understand what this means and thus try to > understand it better by applying it in actual code: > > (yw <- format(posix, "%Y-%V")) >> # [1] "2015-52" "2015-53" "2016-53" "2016-01" > > Which, after checking back with a calendar, would give me reason to > believe that it using %V does in fact seem to work: it's an input to > `format()` and R doesn't seem to ignore it as the correct week numbers > (following ISO 8601) are returned. > > Not wanting to stress this particular aspect any further, though, I > would slightly rephrase my original question: is it possible to use > the ISO 8601 convention for weeknumbers at all (on Windows, using a > German locale setting) and if so, how would I link ISO 8601 > weeknumbers to the correct month of the year?
You are using an undocumented behavior of R's implementation on Windows. If you have a date, it's unambiguous what month and dates should be returned, but I don't think it's quite so easy to say in which month an unspecified day of the week in a particular numbered week might lie. -- David. > > Thanks for help, > Janko > > On Thu, Jan 12, 2017 at 8:37 PM, David Winsemius <dwinsem...@comcast.net> > wrote: >> >>> On Jan 12, 2017, at 8:14 AM, Janko Thyson <janko.thy...@gmail.com> wrote: >>> >>> Dear list, >>> >>> I'm experiencing problems with converting strings of the format >>> "YYYY-<weekofyear>" (e.g. 2016-01, 2016-52) to proper POSIX dates which (I >>> think) I need in order to retrieve the month-of-the-year number. >>> >>> Simpler put: I'd like to match week-of-the-year numbers to >>> month-of-the-year numbers. Ideally, the week-of-the-year number would >>> follow the ISO 8601 convention (i.e. format argument "%V") instead of the >>> US (format argument "%U") or UK (format argument "%W") convention. >>> >>> After posting this to Stackoverflow, I have strong reasons to believe that >>> the issue is caused by Windows: >>> http://stackoverflow.com/questions/41616407/match-iso-8601-week-numbers-to-month-of-year-on-windows-with-german-locale/41617215?noredirect=1#comment70436768_41617215 >>> >>> Example: >>> >>> # ISO 8601 convention: >>> >>> (yw <- format(posix, "%Y-%V")) >> >> The documentation for R datetime format parameters ?strptime says %V is >> ignored on input. >> >> >>> # [1] "2015-52" "2015-53" "2016-53" "2016-01" >>> ywd <- sprintf("%s-1", yw)(as.POSIXct(ywd, format = "%Y-%V-%u")) >> >> The documentation for R datetime format parameters ( = ?strptime) says %V is >> ignored on input. >> >> You should leartn to post plain text to r-help. >> >> -- >> David. >> >> >>> # [1] >>> "2015-01-12 CET" "2015-01-12 CET" "2016-01-12 CET" "2016-01-12 CET"# >>> -> utterly wrong!!! >>> >>> # US convention: >>> (yw <- format(posix, "%Y-%U"))# [1] "2015-51" "2015-52" "2016-00" "2016-01" >>> ywd <- sprintf("%s-1", yw)(as.POSIXct(ywd, format = "%Y-%U-%u"))# [1] >>> "2015-12-21 CET" "2015-12-28 CET" NA "2016-01-04 CET"# >>> -> NA problem for week 00A fellow R user tested this on both macOS and >>> Ubuntu and he didn't encounter the issue: >>> >>> some_dates <- as.POSIXct(c("2015-12-24", "2015-12-31", "2016-01-01", >>> "2016-01-08")) >>> (year_week <- format(some_dates, "%Y %U"))## [1] "2015 51" "2015 52" >>> "2016 00" "2016 01" >>> (year_week_day <- sprintf("%s 1", year_week))## [1] "2015 51 1" "2015 >>> 52 1" "2016 00 1" "2016 01 1" >>> (as.POSIXct(year_week_day, format = "%Y %U %u"))## [1] "2015-12-21 >>> EST" "2015-12-28 EST" "2016-01-04 EST" "2016-01-04 EST" >>> >>> My session info: >>> >>>> sessionInfo() >>> R version 3.3.2 (2016-10-31) >>> Platform: x86_64-w64-mingw32/x64 (64-bit) >>> Running under: Windows >= 8 x64 (build 9200) >>> >>> locale:[1] LC_COLLATE=German_Germany.1252 >>> LC_CTYPE=German_Germany.1252 LC_MONETARY=German_Germany.1252 >>> [4] LC_NUMERIC=C LC_TIME=English_United >>> States.1252 >>> >>> attached base packages:[1] stats graphics grDevices utils >>> datasets methods base >>> >>> other attached packages: >>> [1] fva_0.1.0 digest_0.6.10 readxl_0.1.1 dplyr_0.5.0 >>> plyr_1.8.4 magrittr_1.5 >>> [7] memoise_1.0.0 testthat_1.0.2 roxygen2_5.0.1 devtools_1.12.0 >>> >>> loaded via a namespace (and not attached): >>> [1] Rcpp_0.12.8 lubridate_1.6.0 assertthat_0.1 packrat_0.4.8-1 >>> crayon_1.3.2 withr_1.0.2 >>> [7] R6_2.2.0 DBI_0.5-1 stringi_1.1.2 rstudioapi_0.6 >>> tools_3.3.2 stringr_1.1.0 [13] tibble_1.2 >>> >>> Any idea on how to workaround this issue on Windows? >>> >>> Thanks and best regards, >>> >>> Janko Thyson >>> >>> [[alternative HTML version deleted]] >>> >>> ______________________________________________ >>> R-help@r-project.org mailing list -- To UNSUBSCRIBE and more, see >>> https://stat.ethz.ch/mailman/listinfo/r-help >>> PLEASE do read the posting guide http://www.R-project.org/posting-guide.html >>> and provide commented, minimal, self-contained, reproducible code. >> >> David Winsemius >> Alameda, CA, USA >> David Winsemius Alameda, CA, USA ______________________________________________ R-help@r-project.org mailing list -- To UNSUBSCRIBE and more, see https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.
