[R] lubridate concatenation issue

[arun]

HI,

Thanks for the information.
d1<-ymd_hms("20111231050000")
Sys.setenv(TZ="UTC")
e2<-c(d1)
 e2
#[1] "2011-12-31 05:00:00 UTC"
 Sys.setenv(TZ="EST")
 e1<-c(d1)
 attr(e1,"tzone")<-"UTC"
 e1
#[1] "2011-12-31 05:00:00 UTC"

#Looks similar,
attr(e1,"tzone")
#[1] "UTC"
 attr(e2,"tzone")
#NULL
?c.POSIXct()
     Using ‘c’ on ‘"POSIXlt"’ objects converts them to the current time
     zone, and on ‘"POSIXct"’ objects drops any ‘"tzone"’ attributes
     (even if they are all marked with the same time zone).

So, may be assigning attr(x,"tzone") may be best method
A.K.





----- Original Message -----
From: Peter Ehlers <ehlers at ucalgary.ca>
To: arun <smartpink111 at yahoo.com>
Cc: Andre Zege <azege at yahoo.com>; R help <r-help at r-project.org>
Sent: Friday, November 16, 2012 11:26 AM
Subject: Re: [R] lubridate concatenation issue

On 2012-11-16 04:39, arun wrote:
> HI,
> Sys.setenv(TZ="GMT")
>   c(d)
> #[1] "2011-12-31 GMT"
>
> #or
> Sys.setenv(TZ="UTC")
>   c(d)
> #[1] "2011-12-31 UTC"
>
> Hope it helps.
> A.K.
>

Yes, but c(d) will still not have a 'tzone' attribute.
So the OP is okay as long as his further operations
do not depend on the presence of that attribute.

Peter Ehlers

>
>
> ----- Original Message -----
> From: Andre Zege <azege at yahoo.com>
> To: "r-help at r-project.org" <r-help at r-project.org>
> Cc:
> Sent: Thursday, November 15, 2012 9:36 PM
> Subject: [R] lubridate concatenation issue
>
> I took a look at Hadley's lubridate which seems a very neat package, but i am having a small problem with  concatenating lubridates to build vectors of it. Namely when function c( )  is applied to lubridate seems to change time to a local timezone in this particular case changing the date to previous one.
>
>> d<-ymd('20111231')
>> d
> [1] "2011-12-31 UTC"
>> c(d)
> [1] "2011-12-30 19:00:00 EST"
>
>
>
> Is this the expected behavior and if yes, how could it be avoided for this function and the others that possibly do the same? I mean, i could create the date in my local timezone and avoid this, but if i don't do it, is there an option in environment or functions to avoid this from happening -- otherwise i need to watch out for nasty bugs.
>
>
> Thanks
> Andre
>      [[alternative HTML version deleted]]
>
>
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