[R] Datetime

[Peter Dalgaard]

"COMTE Guillaume" <g.comte at alliance-ir.net> writes:

> Hi all,
> 
> I'm getting confused by date handling.
> 
>  
> 
> I wish to read a date from a file wich is a number of seconds since 1970
> (POSIXct).
> 
> Then i wish to convert this date to a human readable form (POSIXlt)
> 
>  
> 
> By example :
> 
>  
> 
> ctDate<-1132963200 #"Wed Aug 30 14:24:37 2006"
> 
> is(ctDate)
> 
> [1] "numeric" "vector"
> 
>  
> 
> ctDate isn't a numeric vector, it is a POSIXct... none of the clues
> inside the docs has given me the answer, i can't cast it, i can't
> converti t to POSIXlt because it is wrong class (as.POSIX** don't want
> to work...)
> 
>  
> 
> What is the trick ??

It *is* a numeric vector. You need to add it to the epoch time or do
an explicit conversion

> ISOdatetime(1970,1,1,1,0,0)+ctDate # epoch is 01:00 in CET
[1] "2005-11-26 01:00:00 CET"

> structure(ctDate,class="POSIXct")
[1] "2005-11-26 01:00:00 CET"

(Your date seems out of whack by some 24 million seconds...)

-- 
   O__  ---- Peter Dalgaard             Øster Farimagsgade 5, Entr.B
  c/ /'_ --- Dept. of Biostatistics     PO Box 2099, 1014 Cph. K
 (*) \(*) -- University of Copenhagen   Denmark          Ph:  (+45) 35327918
~~~~~~~~~~ - (p.dalgaard at biostat.ku.dk)                  FAX: (+45) 35327907