[R] c(a, b) for POSIXct objects with tzone attributes?

[Spencer Graves]

Hello:


       What is the recommended method for retaining the tzone attributes 
when concatonating POSIXct objects?


> (d1 <- ISOdate(1970,1,1)) # Sets the tzone attribute = GMT
[1] "1970-01-01 12:00:00 GMT"
> (d1.2 <- c(d1, d1)) # c(..) strips the tzone attribute, displays in
the time zone of the operating system
[1] "1970-01-01 04:00:00 PST" "1970-01-01 04:00:00 PST"
> attr(d1.2, 'tzone') <- 'GMT'
> d1.2 # tzone attribute manually restored
[1] "1970-01-01 12:00:00 GMT" "1970-01-01 12:00:00 GMT"


       "c" is a generic function with a method defined for objects of 
class POSIXct, so the results here were what is returned by c.POSIXct 
[as discussed with help('c.POSIXct')].


       Is there some other function like "c2", say, that tries to retain 
attributes where "c" strips all but names?


       Thanks,
       Spencer

-- 
Spencer Graves, PE, PhD
President and Chief Technology Officer
Structure Inspection and Monitoring, Inc.
751 Emerson Ct.
San José, CA 95126
ph:  408-655-4567
web:  www.structuremonitoring.com