changing date by +/- days

I try to use difftimes as much as possible.  For example,

oneday <- as.difftime( 24, units="hours" )
sometime - 10 * oneday

You might also find the lubridate package useful.
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got it, sorry!

structure(1243792800, class = c("POSIXct", "POSIXt"), tzone =
"GMT")-(60*60*24*10)




chuck.01 wrote

Hi, 
Let say I have a date variable like this:

structure(1243792800, class = c("POSIXct", "POSIXt"), tzone = "GMT")
[1] "2009-05-31 18:00:00 GMT"

How can I make it 10 days prior, so:
[1] "2009-05-21 18:00:00 GMT"

I'm randomly selecting dates from a list  and want a  second value a

set #

of days either before or after. 

Thanks ahead of time.

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