Based on the discussion so far, the 1950 issue is due to the timezone and Prof. Riley has established that the 1900 issue is a coding error in printing dates (but not in ISOdate, itself, or in the representation of POSIXct dates).
I assume that the 1900 was found by just playing around but if your data actually does go that far back then note that neither of the above two issues will affect you if you use chron: > require(chron) > chron( paste(3,16,c(1900,1950),sep="/"), out.format="year-m-d") [1] 1900-Mar-16 1950-Mar-16 --- Date: Wed, 19 Nov 2003 17:27:19 +0100 From: Heiko Schaefer <[EMAIL PROTECTED]> To: <[EMAIL PROTECTED]> Subject: RE: [R] ISOdate returns incorrect date? It starts on the 1st of March 1900 to go wrong .... I feel better now that somebody Else these the same effect ;-) -----Original Message----- From: Simon Fear [mailto:[EMAIL PROTECTED] Sent: Mittwoch, 19. November 2003 17:17 To: [EMAIL PROTECTED]; [EMAIL PROTECTED]; [EMAIL PROTECTED] Subject: RE: [R] ISOdate returns incorrect date? Well, I live only a few seconds away from GMT and I also get > ISOdate(1900,6,16,tz="") [1] "1900-06-15 12:00:00 GMT Daylight Time" 15th, not 16th. Was 1900 a strange leap year? I certainly haven't tested thoroughly but note this: > ISOdate(1900,2,16,tz="") [1] "1900-02-16 12:00:00 GMT Standard Time" # 16th OK in February > ISOdate(1900,3,16,tz="") [1] "1900-03-15 12:00:00 GMT Standard Time" # wrong for March Using today's release of rw181beta (up to date or what?) on Win 98 (oh well). > -----Original Message----- > From: Gabor Grothendieck [mailto:[EMAIL PROTECTED] > Sent: 19 November 2003 16:06 > To: [EMAIL PROTECTED]; [EMAIL PROTECTED] > Subject: RE: [R] ISOdate returns incorrect date? > > > Security Warning: > If you are not sure an attachment is safe to open please contact > Andy on x234. There are 0 attachments with this message. > ________________________________________________________________ > > > > ISOdate works, by default, in the GMT timezone. Try: > > ISOdate(1900,6,16,tz="") > ISOdate(1950,6,16,tz="") > > If you don't need timezones and don't want to worry about them you can > alternately use the chron library for your dates and times. > > --- > Date: Wed, 19 Nov 2003 14:58:24 +0100 > From: Heiko Schaefer <[EMAIL PROTECTED]> > To: <[EMAIL PROTECTED]> > Subject: [R] ISOdate returns incorrect date? > > > > > Dear all, > > I have found the following (for me) incomprehensible behaviour of > ISOdate (POSIXct): > > ISOdate(1900,6,16) > [1] "1900-06-15 14:00:00 Westeuropdische Sommerzeit" > > ISOdate(1950,6,16) > [1] "1950-06-16 14:00:00 Westeuropdische Sommerzeit" > > Note that in the first case I get the 15th of June back, not > the 16th as > I would have expected! > This happened under R-1.7.1 on both windows and linux. > > I would greatly appreciate your comments, > > Heiko > > ______________________________________________ > [EMAIL PROTECTED] mailing list > https://www.stat.math.ethz.ch/mailman/listinfo/r-help > > ______________________________________________ > [EMAIL PROTECTED] mailing list > https://www.stat.math.ethz.ch/mailman/listinfo/r-help > Simon Fear Senior Statistician Syne qua non Ltd Tel: +44 (0) 1379 644449 Fax: +44 (0) 1379 644445 email: [EMAIL PROTECTED] web: http://www.synequanon.com Number of attachments included with this message: 0 This message (and any associated files) is confidential and\...{{dropped}} ______________________________________________ [EMAIL PROTECTED] mailing list https://www.stat.math.ethz.ch/mailman/listinfo/r-help