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date/time arithmetic
3 messages · Parlamis Franklin, Gabor Grothendieck
6 days later
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I don't know what is wrong but you could use the numeric class instead of the difftime class as a workaround: x <- Sys.time() y <- x + 3600 diffyx <- as.numeric(y) - as.numeric(x) identical(y - diffyx, x) # TRUE
On 11/23/05, Parlamis Franklin <fparlamis at mac.com> wrote:
On the help page "DateTimeClasses {base}" it says:
"One can add or subtract a number of seconds or a difftime object
from a date-time object, but not add two date-time objects."
However,
> x<-Sys.time(); y<-Sys.time()+3600 > diff<-y-x > x; y; diff
[1] "2005-11-23 19:58:20 GMT" [1] "2005-11-23 20:58:20 GMT" Time difference of 1 hours
> y-diff
[1] "2005-11-23 20:58:19 GMT"
Warning message:
Incompatible methods ("-.POSIXt", "Ops.difftime") for "-"
Do I have the syntax wrong? Or is some conversion of the difftime
object to raw seconds necessary prior to performing arithmetic? And
is the help page wrong?
Thanks.
Franklin
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