[R] POSIXct bug?

[Spencer Graves]

Hi, Gabor: 

      Of course:  time zone vs. GMT. 

       Next question:  Might a simple example that illustrates this be 
added to the help file for "as.POSIXct", and if yes, what should be done 
to make that happen? 

      Thanks. 
      spencer graves

Gabor Grothendieck wrote:

>Spencer Graves <spencer.graves <at> pdf.com> writes:
>
>: 
>: In R 2.0.1 under Windows 2000, at least in some cases, as.POSIXct 
>: adds one to the date: 
>: 
>:  > March1.1959.POSIXct <- as.POSIXct("1959-03-01")
>:  > March1.1959.POSIXlt <- as.POSIXlt("1959-03-01")
>:  >
>:  > (Mar2.59 <- as.Date(March1.1959.POSIXct))
>: [1] "1959-03-02"
>:  > as.Date(March1.1959.POSIXlt)
>: [1] "1959-03-01"
>:  >
>:  > as.Date(as.POSIXct(Mar2.59))
>: [1] "1959-03-02"
>:  > as.Date(as.POSIXct(as.character(Mar2.59)))
>: [1] "1959-03-03"
>:  > print(POSIX.i <- as.POSIXct("1959-03-01"))
>: [1] "1959-03-01 Pacific Standard Time"
>:  > for(i in 1:11){
>: +   print(date.i <- as.Date(POSIX.i))
>: +   print(POSIX.i <- as.POSIXct(as.character(date.i)))
>: + }
>: [1] "1959-03-02"
>: [1] "1959-03-02 Pacific Standard Time"
>: [1] "1959-03-03"
>: [1] "1959-03-03 Pacific Standard Time"
>: [1] "1959-03-04"
>: [1] "1959-03-04 Pacific Standard Time"
>: [1] "1959-03-05"
>: [1] "1959-03-05 Pacific Standard Time"
>: [1] "1959-03-06"
>: [1] "1959-03-06 Pacific Standard Time"
>: [1] "1959-03-07"
>: [1] "1959-03-07 Pacific Standard Time"
>: [1] "1959-03-08"
>: [1] "1959-03-08 Pacific Standard Time"
>: [1] "1959-03-09"
>: [1] "1959-03-09 Pacific Standard Time"
>: [1] "1959-03-10"
>: [1] "1959-03-10 Pacific Standard Time"
>: [1] "1959-03-11"
>: [1] "1959-03-11 Pacific Standard Time"
>: [1] "1959-03-12"
>: [1] "1959-03-12 Pacific Standard Time"
>:  >      
>:       Comments?
>
>I am not sure that the code really speaks for itself.  What is the bug?
>Note that as.Date converts dates relative to GMT, not the current time
>zone.  If you want to convert a POSIXct date to a Date date relative
>to the current timezone you can convert it to character first.  RNews 4/1
>has a table that provides a number of such idioms.
>
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