On Oct 5, 2013, at 4:51 PM, Sean O'Riordain <sean...@acm.org> wrote: > 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. >
Just to clarify since the Joshua's comment was ambiguous (and in part plain wrong) - R's POSIXct has no such limit since it doesn't use integers, so that is not really the issue here. As the original post suggested there may be a bug in handing some cases where conversions hit the system libraries (that may truncate to integers) and some cases may be worked around - and that remains to be investigated. Cheers, Simon > 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 > ______________________________________________ R-devel@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-devel
