On 23/09/2013 22:43, MacQueen, Don wrote:
The very first response, from Jeff Newmiller, included a link http://efele.net/maps/tz/world/ which says it has offers a shapefile of timezones of the world.An outline of a solution, then it to download the shapefile load it into R input your lat/long data into R use the over() function in the sp package Of course there are many details amongst those steps; I would suggest r-sig-geo would be the place for help with those details. It remains to be seen whether the way in which the timezones are identified in that shapefile is compatible with how timezones are identified in R POSIXt classes (R uses the OS for this). Daylight savings time information is, I believe, provided by the OS for at least some time zones, but I don't know if its provided for all of them.
It needs to be. That is why the tzone databases are so large and complex and change several times a year.
Actually, the info is provided by the OS except on Windows where the Olsen/IANA database is used (as it is by almost all other current OSes). So timezone names are fairly portable.
I thought I read in this thread that these were recordings at sea: see the caveats at that URL (it only applies on land ...).
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