[R] Convert Unix (Epoch) timestamp to DD/MM/YY and HH:MM:SS

[David Winsemius]

On Jul 20, 2010, at 9:26 AM, Jim Hargreaves wrote:

> Dear List,
>
> After much searching with no success, I would like to ask how I can  
> convert a unix/POSIX time (seconds since Jan 01, 1970) into a string  
> like "01/01/1970 00:00"
>
> This is probably easily done with a system(date...) but it would be  
> great if I could do it in R.

By default DateTime objects are printed similarly to your specification:

 > Sys.time()
[1] "2010-07-20 09:34:36 EDT"

 > as.numeric( Sys.time() ) # the internal representation
[1] 1279632906

The default format for the default print function is YYYY-MM-DD HH:MM  
TZ. You can find the format codes with:

?strptime

 > print(Sys.time(), format="%m/%d/%Y %H:%M") # your request is  
ambiguous w.r.t month and day order
[1] "07/20/2010 09:39 EDT"
>

-- 

David Winsemius, MD
West Hartford, CT