On Thu, 10 Jan 2008, dankelley wrote: > > #QUESTION# > > Is there a way to calculate the offset between timezones, e.g. from "AST" to > "GMT"? > > #DETAILS# > > I am working with data files that use local time, and that indicate the > timezone by e.g. "AST" (Atlantic Standard Time, my local time) in a header.
The problem is that AST is not a valid timezone (at least on my Mac), so is being ignored. I think you want "America/Halifax". (Works for me on Leopard as well as on Linux.) The documentation for R-devel may help here: https://svn.r-project.org/R/trunk/src/library/base/man/timezones.Rd But earlier versions do say things like If a timezone is needed and that specified is invalid on your system, what happens is system-specific but it will probably be ignored. > I was guessing that > >> ISOdatetime(2008,1,1,1,0,0,tz="GMT") - >> ISOdatetime(2008,1,1,1,0,0,tz="AST") > > would work, but it gives a difference of 0. However, when I do > >> ISOdatetime(2008,1,1,1,0,0,tz="GMT") - ISOdatetime(2008,1,1,1,0,0) > > I get a -4h offset, which is correct. The odd thing is, I am in AST time, > as shown by the following. > >> ISOdatetime(2008,1,1,1,0,0) > [1] "2008-01-01 01:00:00 AST" > > #SYSTEM# > > Mac OS X system, with R 2.6.1 > > #PS# > > I am aware that this sort of thing is system dependent, and so there may not > be a general solution. But even if I can only get it working on my own > particular system, I'd be happy! > -- Brian D. Ripley, [EMAIL PROTECTED] Professor of Applied Statistics, http://www.stats.ox.ac.uk/~ripley/ University of Oxford, Tel: +44 1865 272861 (self) 1 South Parks Road, +44 1865 272866 (PA) Oxford OX1 3TG, UK Fax: +44 1865 272595 ______________________________________________ R-help@r-project.org mailing list 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.
