[R] Problem with as.POSIXct on dates object

[Remko Duursma]

> as.POSIXct.dates does not make use of tz:

Ok, but it is supposed to, right? Or maybe the documentation can be
updated, because ?as.POSIXct does seem to imply the timezone is used
(as it is for other methods of as.POSIXct).

thanks,
Remko




-------------------------------------------------
Remko Duursma
Post-Doctoral Fellow

Centre for Plants and the Environment
University of Western Sydney
Hawkesbury Campus
Richmond NSW 2753

Dept of Biological Science
Macquarie University
North Ryde NSW 2109
Australia

Mobile: +61 (0)422 096908



On Mon, Jul 20, 2009 at 1:41 PM, Gabor
Grothendieck<ggrothendieck at gmail.com> wrote:
> as.POSIXct.dates does not make use of tz:
>
>> as.POSIXct.dates
> function (x, ...)
> {
>    if (inherits(x, "dates")) {
>        z <- attr(x, "origin")
>        x <- as.numeric(x) * 86400
>        if (length(z) == 3L && is.numeric(z))
>            x <- x + as.numeric(ISOdate(z[3L], z[1L], z[2L],
>                0))
>        return(structure(x, class = c("POSIXt", "POSIXct")))
>    }
>    else stop(gettextf("'%s' is not a \"dates\" object",
> deparse(substitute(x))))
> }
> <environment: namespace:base>
>
>
> On Sun, Jul 19, 2009 at 11:30 PM, Remko Duursma<remkoduursma at gmail.com> wrote:
>> Dear R-helpers,
>>
>>
>> I have a problem converting an object made with the 'chron' function
>> to a POSIXct object:
>>
>> # Make date based on DOY
>> dat <- chron(dates=232, origin.=c(month=1, day=1, year=2008))
>>
>> dat
>> #[1] 08/20/08
>>
>> # Converting to POSIXct uses current timezone (Sydney):
>> as.POSIXct(dat)
>> #[1] "2008-08-20 10:00:00 EST"
>>
>> # Setting GMT timezone has no effect?
>> as.POSIXct(dat, tz="GMT")
>> #[1] "2008-08-20 10:00:00 EST"
>>
>> # But to POSIXlt works fine:
>> as.POSIXlt(dat, tz="GMT")
>> #[1] "2008-08-20 GMT"
>>
>> Is this behavior expected? If so, can you explain why?
>>
>> thanks for your help,
>> Remko
>>
>>
>>
>> -------------------------------------------------
>> Remko Duursma
>> Post-Doctoral Fellow
>>
>> Centre for Plants and the Environment
>> University of Western Sydney
>> Hawkesbury Campus
>> Richmond NSW 2753
>>
>> Dept of Biological Science
>> Macquarie University
>> North Ryde NSW 2109
>> Australia
>>
>> Mobile: +61 (0)422 096908
>>
>> ______________________________________________
>> R-help at r-project.org mailing list
>> https://stat.ethz.ch/mailman/listinfo/r-help
>> PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
>> and provide commented, minimal, self-contained, reproducible code.
>>
>