On 10-Mar-05 Sander Oom wrote: > Hi Yyan, > > The proj4R package by Roger Bivand will allow you to project data in > many ways and directions. > > http://spatial.nhh.no/R/Devel/proj4R-pkg.pdf > > It uses the proj libraries from: > > http://www.remotesensing.org/proj/ > > Not sure where you would derive the time zone! > > Good luck, > > Sander.
While there is a longitude-based "nominal" time-zone structure (0deg E is the centre of Zone 0 which extends for 7.5deg either side; successive time-zones move round by 15deg), this does not apply cleanly to the time-shifts adopted in different places for local time. A World map of regions with different local-time offsets is a crazy patchwork, with all sorts of contradictory looking regions. For instance, the "-0700" region of the USA extends from approx -0830 to approx -0620, covering over 2 hours, and parts of "-0800" touch the -0700 line and are more than 0100 East of parts of "-0700". Even worse can be found over the Indian/Central Asian and Malaysian parts of the world, where time-shifts of 30 miniutes are also frequent (and, according to my Atlas, one country, Nepal, has "5&2/3" i.e. +0540!). As Sander says, "Not sure where you would derive the time zone!". Unless you can refer a (long,lat) position to a look-up table, you can't predict what the zone will be to less the 1 hour (except of course for the "nominal" time-zones by 15deg sectors). I've never encountered a "digital" version of such a table (my Atlas must be based on one, though). Best wishes, Ted. > yyan liu wrote: >> Hi: >> Is there any function in R which can convert the >> long/lat to UTM(Universal Transverse Mercator)? >> There are quite a few converters on Internet. >> However, the interface is designed as input->output >> which I can not convert lots of locations at the same >> time. >> Another question is whether there is a function in R >> which can tell the time zone from the location's >> lat/long? >> Thank you! >> >> liu >> >> ______________________________________________ >> R-help@stat.math.ethz.ch mailing list >> https://stat.ethz.ch/mailman/listinfo/r-help >> PLEASE do read the posting guide! >> http://www.R-project.org/posting-guide.html >> >> > > -- > -------------------------------------------- > Dr. Sander P. Oom > Animal, Plant and Environmental Sciences, > University of the Witwatersrand > Private Bag 3, Wits 2050, South Africa > Tel (work) +27 (0)11 717 64 04 > Tel (home) +27 (0)18 297 44 51 > Fax +27 (0)18 299 24 64 > Email [EMAIL PROTECTED] > Web www.oomvanlieshout.net/sander > > ______________________________________________ > R-help@stat.math.ethz.ch mailing list > https://stat.ethz.ch/mailman/listinfo/r-help > PLEASE do read the posting guide! > http://www.R-project.org/posting-guide.html -------------------------------------------------------------------- E-Mail: (Ted Harding) <[EMAIL PROTECTED]> Fax-to-email: +44 (0)870 094 0861 Date: 10-Mar-05 Time: 09:47:25 ------------------------------ XFMail ------------------------------ ______________________________________________ R-help@stat.math.ethz.ch mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide! http://www.R-project.org/posting-guide.html