check again your results with as.integer() replaced by round(); check also ?as.integer for its usage.
I hope it helps. Best, Dimitris ---- Dimitris Rizopoulos Ph.D. Student Biostatistical Centre School of Public Health Catholic University of Leuven Address: Kapucijnenvoer 35, Leuven, Belgium Tel: +32/(0)16/336899 Fax: +32/(0)16/337015 Web: http://www.med.kuleuven.be/biostat/ http://www.student.kuleuven.be/~m0390867/dimitris.htm ----- Original Message ----- From: <[EMAIL PROTECTED]> To: <r-help@stat.math.ethz.ch> Sent: Tuesday, February 21, 2006 4:48 PM Subject: [R] Number of Days Between Dates: Incorrect Results For DateCalucations. > In some cases, incorrect results are produced by the code below > intended to > calculate the number of days between 2 dates. The year in question > was a > leap year. > > Note the results for 2004-04-04 and 2004-04-05 are the same! They > should be > 37 and 38 respectively. > >> as.integer(as.POSIXct("2004-04-02") - as.POSIXct("2004-02-27")) > [1] 35 >> as.integer(as.POSIXct("2004-04-03") - as.POSIXct("2004-02-27")) > [1] 36 >> as.integer(as.POSIXct("2004-04-04") - as.POSIXct("2004-02-27")) > [1] 37 >> as.integer(as.POSIXct("2004-04-05") - as.POSIXct("2004-02-27")) > [1] 37 >> as.integer(as.POSIXct("2004-04-06") - as.POSIXct("2004-02-27")) > [1] 38 > > > >> as.integer(difftime(as.POSIXct("2004-04-06"), > as.POSIXct("2004-02-27"),units="days")) > [1] 38 >> as.integer(difftime(as.POSIXct("2004-04-04"), > as.POSIXct("2004-02-27"),units="days")) > [1] 37 >> as.integer(difftime(as.POSIXct("2004-04-05"), > as.POSIXct("2004-02-27"),units="days")) > [1] 37 > > It appears that difftime() and "-" are producing invalid results. > > > Regards, > > Gerald Herbert > > ______________________________________________ > R-help@stat.math.ethz.ch mailing list > https://stat.ethz.ch/mailman/listinfo/r-help > PLEASE do read the posting guide! > http://www.R-project.org/posting-guide.html > Disclaimer: http://www.kuleuven.be/cwis/email_disclaimer.htm ______________________________________________ R-help@stat.math.ethz.ch mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide! http://www.R-project.org/posting-guide.html