Some people (luckily not me anymore!) working with mortgages and pensions need to calculate up to 40 years into the future for the payment schedule.
On 5 October 2013 02:37, Joshua Ulrich <josh.m.ulr...@gmail.com> wrote: > On Fri, Oct 4, 2013 at 8:02 PM, Imanuel Costigan <i.costi...@me.com> wrote: >> Thanks for the responses and quoting the timezone help file. >> >> I am assuming that in order to determine the wday element of POSIXlt, R does >> the necessary calculations in Julian time (via POSIXct). Based on this >> excerpt from ?DateTimeClasses, it looks like R is responsible for >> determining time zones post 2037 (the example I gave was in 2038). So it >> could be an R issue. >> > It's an issue with size of the largest number you can store in a > signed integer, which is not specific to R. > >> .POSIXct(.Machine$integer.max, tz="UTC") > [1] "2038-01-19 03:14:07 UTC" > > Dates larger than that cannot be represented by a signed integer. It > could be worked around, but it's not trivial because R would have to > use something other than the tm C struct. Luckily, there's a decade > or two before it starts to become a pressing issue. :) > >>> ‘"POSIXct"’ objects may also have an attribute ‘"tzone"’, a >>> character vector of length one. If set to a non-empty value, it >>> will determine how the object is converted to class ‘"POSIXlt"’ >>> and in particular how it is printed. This is usually desirable, >>> but if you want to specify an object in a particular timezone but >>> to be printed in the current timezone you may want to remove the >>> ‘"tzone"’ attribute (e.g. by ‘c(x)’). >>> >>> Unfortunately, the conversion is complicated by the operation of >>> time zones and leap seconds (24 days have been 86401 seconds long >>> so far: the times of the extra seconds are in the object >>> ‘.leap.seconds’). **The details of this are entrusted to the OS >>> services where possible. This always covers the period 1970-2037, >>> and on most machines back to 1902 (when time zones were in their >>> infancy). Outside the platform limits we use our own C code. >> >> >> On 05/10/2013, at 12:59 AM, Scott Kostyshak <skost...@princeton.edu> wrote: >> >>> On Fri, Oct 4, 2013 at 6:11 AM, Imanuel Costigan <i.costi...@me.com> wrote: >>>> Wanted to raise two questions: >>>> >>>> 1. Is bugs.r-project.org down? I haven't been able to reach it for two or >>>> three days: >>> >>> Yes. Quote from Duncan: >>> >>> ... the server is currently down. The volunteer who runs the server is >>> currently away from his office, so I expect it won't get fixed until he >>> gets back in a few days. >>> >>> https://stat.ethz.ch/pipermail/r-help/2013-October/360958.html >>> >>> Scott >>> >>>> >>>> ``` >>>> ping bugs.r-project.org >>>> PING rbugs.research.att.com (207.140.168.137): 56 data bytes >>>> Request timeout for icmp_seq 0 >>>> Request timeout for icmp_seq 1 >>>> Request timeout for icmp_seq 2 >>>> Request timeout for icmp_seq 3 >>>> Request timeout for icmp_seq 4 >>>> Request timeout for icmp_seq 5 >>>> Request timeout for icmp_seq 6 >>>> ``` >>>> >>>> 2. Is wday element of POSIXlt meant to be timezone invariant? You would >>>> expect the wday element to be invariant to the timezone of a date. That >>>> is, the same date/time instant of 5th October 2013 in both >>>> Australia/Sydney and UTC should be a Saturday (i.e. wday = 6). And indeed >>>> that is the case with 1 min past midnight on 5 October 2013: >>>> >>>> ``` >>>> library(lubridate) >>>> d_utc <- ymd_hms(20131005000001, tz='UTC') >>>> d_local <- ymd_hms(20131005000001, tz='Australia/Sydney') >>>> as.POSIXlt(x=d_utc, tz=tz(d_utc))$wday # 6 >>>> as.POSIXlt(x=d_local, tz=tz(d_local))$wday # 6 >>>> ``` >>>> >>>> But this isn't always the case. For example, >>>> >>>> ``` >>>> d_utc <- ymd_hms(20381002000001, tz='UTC') >>>> d_local <- ymd_hms(20381002000001, tz='Australia/Sydney') >>>> as.POSIXlt(x=d_utc, tz=tz(d_utc))$wday # 6 >>>> as.POSIXlt(x=d_local, tz=tz(d_local))$wday # 5 >>>> ``` >>>> >>>> Is this expected behaviour? I would have expected a properly encoded >>>> date/time of 2 Oct 2038 to be a Saturday irrespective of its time zone. >>>> >>>> Obligatory system dump: >>>> >>>> ``` >>>>> sessionInfo() >>>> R version 3.0.1 (2013-05-16) >>>> Platform: x86_64-apple-darwin12.4.0 (64-bit) >>>> >>>> locale: >>>> [1] en_AU.UTF-8/en_AU.UTF-8/en_AU.UTF-8/C/en_AU.UTF-8/en_AU.UTF-8 >>>> >>>> attached base packages: >>>> [1] stats graphics grDevices utils datasets methods base >>>> >>>> other attached packages: >>>> [1] lubridate_1.3.0 testthat_0.7.1 devtools_1.3 >>>> >>>> loaded via a namespace (and not attached): >>>> [1] colorspace_1.2-4 dichromat_2.0-0 digest_0.6.3 evaluate_0.5.1 >>>> [5] ggplot2_0.9.3.1 grid_3.0.1 gtable_0.1.2 httr_0.2 >>>> [9] labeling_0.2 MASS_7.3-29 memoise_0.1 munsell_0.4.2 >>>> [13] parallel_3.0.1 plyr_1.8 proto_0.3-10 >>>> RColorBrewer_1.0-5 >>>> [17] RCurl_1.95-4.1 reshape2_1.2.2 scales_0.2.3 stringr_0.6.2 >>>> [21] tools_3.0.1 whisker_0.3-2 >>>> >>>> ``` >>>> >>>> Using R compiled by homebrew [1]. But also experiencing the same bug using >>>> R installed on Windows 7 from the CRAN binaries. >>>> >>>> For those interested, I've also noted this on the `lubridate` Github >>>> issues page [2], even though this doesn't appear to be a lubridate issue. >>>> >>>> Thanks for any help. >>>> >>>> [1] http://brew.sh >>>> [2] https://github.com/hadley/lubridate/issues/209 >>>> >>>> ______________________________________________ >>>> R-devel@r-project.org mailing list >>>> https://stat.ethz.ch/mailman/listinfo/r-devel >>> >>> >>> -- >>> Scott Kostyshak >>> Economics PhD Candidate >>> Princeton University >> >> ______________________________________________ >> 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 ______________________________________________ R-devel@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-devel
