[R] POSIX time zone codes

[Prof Brian Ripley]

On Tue, 7 Mar 2006, Jason Horn wrote:

> Thank you again Gabor, that did the trick.  Any thoughts on where I
> go go for a reference for these time codes?  Where did you get
> "CDT6CST" from?  Or is this just one of those things that is "common
> knowledge" in UNIX circles.
>
> To the R developers:  I recommend a sentence be added to the manual
> for as.POSIXxx such as "vales for tz are system dependent, examples
> for common systems are....."

You mean repeating what is already there:

       tz: A timezone specification to be used for the conversion, _if
           one is required_.  System-specific, but '""' is the current
           timezone, and '"GMT"' is UTC (Coordinated Universal Time, in
           French).

?  What are `common systems'?

If you have access to such a set of systems and can provide a 
comprehensive set of (tested) examples please provide a patch.  The POSIX 
specification is at

http://www.opengroup.org/onlinepubs/009695399/basedefs/xbd_chap08.html

under TZ.

You are expecting R to give you information about your OS, and that's 
an unreasonable expectation.


> Thanks!
>
>
> On Mar 7, 2006, at 9:00 AM, Gabor Grothendieck wrote:
>
>> Only "" and "GMT" are really guaranteed to work on all systems
>> since the time zones are system dependent but try: "CDT6CST"
>> and see if that works on your system.
>>
>>
>> On 3/7/06, Jason Horn <jhorn at bu.edu> wrote:
>>> Whoops,
>>>
>>> [EDIT]
>>>
>>> as.POSIX(x, tz="UTC")  ... works, gives UTC times
>>> as.POSIX(x, tz="EST")  ... works, gives EST times
>>>
>>> as.POSIX(x, tz="CST")  ... does NOT work, gives UTC times
>>>
>>> [/EDIT]
>>>
>>> On Mar 7, 2006, at 8:05 AM, Jason Horn wrote:
>>>
>>>> as.POSIX(x, tz="UTC")  ... works, gives UTC times
>>>> as.POSIX(x, tz="UTC")  ... works, gives EST times
>>>>
>>>> as.POSIX(x, tz="CST")  ... does NOT work, gives UTC times

-- 
Brian D. Ripley,                  ripley at stats.ox.ac.uk
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