Automatic time zone conversion
Note that even that will not reliably work on all platforms. The only values for the tz= argument that reliably work across platforms are tz = "" and tz = "GMT". (See RNews 4/1 Help Desk.) In fact, entering the above code into my machine > R.version.string # Windows XP [1] "R version 2.2.0, 2005-10-24" gives a different answer than on your machine: > as.POSIXct(as.character(strptime(cdate,format="%Y-%m-%d_%H:%M:%S")), + tz="CST")+(8*3600) [1] "2000-05-11 08:00:00 CST" Also if by CST you mean Central Standard Time as in Chicago, Houston and Winnipeg then its not 8 hours from GMT. See: http://www.stacken.kth.se/~kvickers/timezone.html Could it be that you just want to read it in as GMT but display it in the current time zone? If so, try this: x <- as.POSIXct(chartr("_", " ", cdate), tz = "GMT") attr(x, "tzone") <- NULL
On 12/5/05, simon <sentientc at gmail.com> wrote:
Dear R-help, I was trying to convert a date and time record extracted from a fortran subroutine I worte and I encounter some problem. The data read in time and date in a format like "2000-05-11_01:00:00.0000" in fortran output. It is in GMT. I need to convert it to CST (GMT+8). I did the following steps.
> cdate
[1] "2000-05-11_01:00:00.0000\005\003" # I am not sure why the extra characters at the end but it doesn't affect the strptime function so I just ingored it.
> strptime(cdate,format="%Y-%m-%d_%H:%M:%S")
[1] "2000-05-11 01:00:00" # In order to incoporate GMT into the record, I use paste function to stick it in.
>as.POSIXct(as.character(strptime(cdate,format="%Y-%m-%d_%H:%M:%S")),tz="GMT")
[1] "2000-05-11 01:00:00 GMT" #It is easier to just do a arthmatic to convert the timezone and ingore this attribute like
>
as.POSIXct(as.character(strptime(cdate,format="%Y-%m-%d_%H:%M:%S")),tz="CST")+(8*3600) [1] "2000-05-11 09:00:00 CST" I was wondering if there is a simpler method to do this. Thanks in advance, Simon
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