R help - Aug 2006 - Datetime

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 ??

Any ideas would be great

thks

COMTE Guillaume

 


	[[alternative HTML version deleted]]

"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             ?ster Farimagsgade 5, Entr.B
  c/ /'_ --- Dept. of Biostatistics     PO Box 2099, 1014 Cph. K
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