[R] time zone conversion

[McGehee, Robert]

Well, I'll go ahead and (partially) answer my own question.

This seems to do the trick for Britain:
> as.POSIXlt(as.POSIXct("2007-04-01 12:00:00"), tz="GB")
[1] "2007-04-01 17:00:00 BST"

(And it also points out that I got my conversions wrong in my toy
example!)

I had originally tried this by setting the 'tz' argument using
'as.POSIXct', but this didn't work for some reason (hence the post)

> as.POSIXct(as.POSIXct("2007-04-01 12:00:00"), tz="GB")
[1] "2007-04-01 12:00:00 EDT"

Hopefully I can figure out from the links what the Tokyo time zone is
called. Sorry for the noise!

> R.version
               _                           
platform       x86_64-unknown-linux-gnu    
arch           x86_64                      
os             linux-gnu                   
system         x86_64, linux-gnu           
status                                     
major          2                           
minor          6.1                         
year           2007                        
month          11                          
day            26                          
svn rev        43537                       
language       R                           
version.string R version 2.6.1 (2007-11-26)
> 

-----Original Message-----
From: McGehee, Robert 
Sent: Monday, April 28, 2008 4:27 PM
To: r-help
Subject: time zone conversion

Hello,

I'm trying to convert times in the EST/EDT (New York) format to times in
the GMT/BST (London) and UTC+9 format (Tokyo). That is, if I know what
time it is in New York, what is local time in London and Tokyo?

Ex:
Here's the conversion from New York EST/EDT time to London's GMT/BST
time zone for three days in 2007. Note that the US and London change to
daylight savings on different days (Tokyo doesn't use daylight savings
at all), so this conversion is non-trivial.

2007-03-01 12:00:00 EST = 2007-03-01 17:00:00 GMT
2007-03-15 12:00:00 EDT = 2007-03-01 16:00:00 GMT
2007-04-01 12:00:00 EDT = 2007-03-01 17:00:00 BST

Is any of the time zone/daylight savings information coded up somewhere?

Thanks,
Robert

Robert McGehee, CFA
Geode Capital Management, LLC
One Post Office Square, 28th Floor | Boston, MA | 02109
Tel: 617/392-8396    Fax:617/476-6389
mailto:robert.mcgehee at geodecapital.com



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