I would like all three of these calculations to give an answer in days (or at least the same units):> as.POSIXct("1971-08-01 00:00:00") - as.POSIXct("1971-08-01 00:00:00")Time difference of 0 secs> > as.POSIXct("1971-08-01 12:00:00") - as.POSIXct("1971-08-01 00:00:00")Time difference of 12 hours> > as.POSIXct("1971-09-01 00:00:00") - as.POSIXct("1971-08-01 00:00:00")Time difference of 31 days>What is the best way to do this? Tom -- View this message in context: http://www.nabble.com/Units-of-Difference-Between-Two-Dates-tp17251994p17251994.html Sent from the R help mailing list archive at Nabble.com.
Tom La Bone wrote:> I would like all three of these calculations to give an answer in days (or at > least the same units): > >> as.POSIXct("1971-08-01 00:00:00") - as.POSIXct("1971-08-01 00:00:00") > Time difference of 0 secs >> as.POSIXct("1971-08-01 12:00:00") - as.POSIXct("1971-08-01 00:00:00") > Time difference of 12 hours >> as.POSIXct("1971-09-01 00:00:00") - as.POSIXct("1971-08-01 00:00:00") > Time difference of 31 days > > What is the best way to do this? > > Tom >difftime(as.POSIXct("1971-08-01 00:00:00"), as.POSIXct("1971-08-01 00:00:00"), units="days") and so on ... Uwe Ligges
On Thu, 15 May 2008, Tom La Bone wrote:> > I would like all three of these calculations to give an answer in days (or at > least the same units): > >> as.POSIXct("1971-08-01 00:00:00") - as.POSIXct("1971-08-01 00:00:00") > Time difference of 0 secs >> >> as.POSIXct("1971-08-01 12:00:00") - as.POSIXct("1971-08-01 00:00:00") > Time difference of 12 hours >> >> as.POSIXct("1971-09-01 00:00:00") - as.POSIXct("1971-08-01 00:00:00") > Time difference of 31 days >> > > What is the best way to do this?Use difftime() explicitly. -- Brian D. Ripley, ripley at stats.ox.ac.uk Professor of Applied Statistics, http://www.stats.ox.ac.uk/~ripley/ University of Oxford, Tel: +44 1865 272861 (self) 1 South Parks Road, +44 1865 272866 (PA) Oxford OX1 3TG, UK Fax: +44 1865 272595