RE: [R] Chron, as.POSIXct problem
From: Brian Beckage [EMAIL PROTECTED] Thanks to all who responded to my posting. At 11:39 AM -0500 11/12/03, Gabor Grothendieck wrote: You are being hit by a timezone problem. Its not really shifting the days by one. Its working in the GMT timezone, not yours. If you can accept a date format that chron supports then this is the easiest solution since chron does not support timezones and so can't give you such problems in the first place. For example, the following stays in chron the whole time: format(datesTest, format=m/day/year) [1] Oct/01/1952 Oct/02/1952 Oct/03/1952 If you must convert to POSIXt to take advantage of a format only supported by POSIXt then use POSIXlt and specify the timezone explictly: format(as.POSIXlt(datesTest,tz=GMT), %m/%d/%Y) [1] 10/01/1952 10/02/1952 10/03/1952 This solved the problem using as.POSIXlt(). I guess the tz argument doesn't solve the problem using as.POSIXct(). In any case, I'm able to use as.POSIXlt() in my current application. You can use POSIXct but its a bit trickier. Assuming datesTest is a chron vector, as before you can do this. format(as.POSIXct(datesTest), %m/%d/%Y, tz=GMT) # right Note that in this case you have to use the tz parameter on format, NOT on as.POSIXct: format(as.POSIXct(datesTest, tz=GMT), %m/%d/%Y) # wrong __ [EMAIL PROTECTED] mailing list https://www.stat.math.ethz.ch/mailman/listinfo/r-help
[R] Chron, as.POSIXct problem
Dear R list, I noticed the following 'problem' when changing the format of dates created with seq.dates() (from the Chron library) using as.POSIXct() (R 1.8.0 on OSX 10.2.8): datesTest-seq.dates(from=10/01/1952, length=3, by=days); datesTest [1] 10/01/52 10/02/52 10/03/52 # Now changing the format to show year as 1952. datesTest-format(as.POSIXct(datesTest), %m/%d/%Y) datesTest [1] 09/30/1952 10/01/1952 10/02/1952 The dates were shifted by one day. The work around is simple enough, e.g., datesTest-format(as.POSIXct(datesTest+1), %m/%d/%Y) [1] 10/01/1952 10/02/1952 10/03/1952 but I wonder if this is the intended behavior? Brian __ [EMAIL PROTECTED] mailing list https://www.stat.math.ethz.ch/mailman/listinfo/r-help
Re: [R] Chron, as.POSIXct problem
Does not happen on Solaris or Linux, so looks like a MacOS X problem. Here is some crosschecks: unclass(datesTest) [1] -6301 -6300 -6299 attr(,format) [1] m/d/y attr(,origin) month day year 1 1 1970 unclass(as.POSIXct(datesTest)) [1] -544406400 -54432 -544233600 On Wed, 12 Nov 2003, Brian Beckage wrote: Dear R list, I noticed the following 'problem' when changing the format of dates created with seq.dates() (from the Chron library) using as.POSIXct() (R 1.8.0 on OSX 10.2.8): datesTest-seq.dates(from=10/01/1952, length=3, by=days); datesTest [1] 10/01/52 10/02/52 10/03/52 # Now changing the format to show year as 1952. datesTest-format(as.POSIXct(datesTest), %m/%d/%Y) datesTest [1] 09/30/1952 10/01/1952 10/02/1952 The dates were shifted by one day. The work around is simple enough, e.g., datesTest-format(as.POSIXct(datesTest+1), %m/%d/%Y) [1] 10/01/1952 10/02/1952 10/03/1952 but I wonder if this is the intended behavior? Brian __ [EMAIL PROTECTED] mailing list https://www.stat.math.ethz.ch/mailman/listinfo/r-help -- Brian D. Ripley, [EMAIL PROTECTED] 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, UKFax: +44 1865 272595 __ [EMAIL PROTECTED] mailing list https://www.stat.math.ethz.ch/mailman/listinfo/r-help
Re: [R] Chron, as.POSIXct problem
Prof Brian Ripley [EMAIL PROTECTED] wrote: Does not happen on Solaris or Linux, so looks like a MacOS X problem. It does not happen on my Mac G4 box (R 1.8.0 on MacOSX 10.2.6). --Philippe Here is some crosschecks: unclass(datesTest) [1] -6301 -6300 -6299 attr(,format) [1] m/d/y attr(,origin) month day year 1 1 1970 unclass(as.POSIXct(datesTest)) [1] -544406400 -54432 -544233600 On Wed, 12 Nov 2003, Brian Beckage wrote: Dear R list, I noticed the following 'problem' when changing the format of dates created with seq.dates() (from the Chron library) using as.POSIXct() (R 1.8.0 on OSX 10.2.8): datesTest-seq.dates(from=10/01/1952, length=3, by=days); datesTest [1] 10/01/52 10/02/52 10/03/52 # Now changing the format to show year as 1952. datesTest-format(as.POSIXct(datesTest), %m/%d/%Y) datesTest [1] 09/30/1952 10/01/1952 10/02/1952 The dates were shifted by one day. The work around is simple enough, e.g., datesTest-format(as.POSIXct(datesTest+1), %m/%d/%Y) [1] 10/01/1952 10/02/1952 10/03/1952 but I wonder if this is the intended behavior? Brian __ [EMAIL PROTECTED] mailing list https://www.stat.math.ethz.ch/mailman/listinfo/r-help -- Brian D. Ripley, [EMAIL PROTECTED] 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, UKFax: +44 1865 272595 __ [EMAIL PROTECTED] mailing list https://www.stat.math.ethz.ch/mailman/listinfo/r-help -- Philippe __ [EMAIL PROTECTED] mailing list https://www.stat.math.ethz.ch/mailman/listinfo/r-help
RE: [R] Chron, as.POSIXct problem
You are being hit by a timezone problem. Its not really shifting the days by one. Its working in the GMT timezone, not yours. If you can accept a date format that chron supports then this is the easiest solution since chron does not support timezones and so can't give you such problems in the first place. For example, the following stays in chron the whole time: format(datesTest, format=m/day/year) [1] Oct/01/1952 Oct/02/1952 Oct/03/1952 If you must convert to POSIXt to take advantage of a format only supported by POSIXt then use POSIXlt and specify the timezone explictly: format(as.POSIXlt(datesTest,tz=GMT), %m/%d/%Y) [1] 10/01/1952 10/02/1952 10/03/1952 Its because of subtle problems like this that I think that some sort of naive (i.e. non-timezone) time such as chron or an alternative, should be in the base to encourage wider use. --- Date: Wed, 12 Nov 2003 10:05:39 -0500 From: Brian Beckage [EMAIL PROTECTED] To: [EMAIL PROTECTED] Subject: [R] Chron, as.POSIXct problem Dear R list, I noticed the following 'problem' when changing the format of dates created with seq.dates() (from the Chron library) using as.POSIXct() (R 1.8.0 on OSX 10.2.8): datesTest-seq.dates(from=10/01/1952, length=3, by=days); datesTest [1] 10/01/52 10/02/52 10/03/52 # Now changing the format to show year as 1952. datesTest-format(as.POSIXct(datesTest), %m/%d/%Y) datesTest [1] 09/30/1952 10/01/1952 10/02/1952 The dates were shifted by one day. The work around is simple enough, e.g., datesTest-format(as.POSIXct(datesTest+1), %m/%d/%Y) [1] 10/01/1952 10/02/1952 10/03/1952 but I wonder if this is the intended behavior? Brian __ [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
RE: [R] Chron, as.POSIXct problem
Thanks to all who responded to my posting. At 11:39 AM -0500 11/12/03, Gabor Grothendieck wrote: You are being hit by a timezone problem. Its not really shifting the days by one. Its working in the GMT timezone, not yours. If you can accept a date format that chron supports then this is the easiest solution since chron does not support timezones and so can't give you such problems in the first place. For example, the following stays in chron the whole time: format(datesTest, format=m/day/year) [1] Oct/01/1952 Oct/02/1952 Oct/03/1952 If you must convert to POSIXt to take advantage of a format only supported by POSIXt then use POSIXlt and specify the timezone explictly: format(as.POSIXlt(datesTest,tz=GMT), %m/%d/%Y) [1] 10/01/1952 10/02/1952 10/03/1952 This solved the problem using as.POSIXlt(). I guess the tz argument doesn't solve the problem using as.POSIXct(). In any case, I'm able to use as.POSIXlt() in my current application. Its because of subtle problems like this that I think that some sort of naive (i.e. non-timezone) time such as chron or an alternative, should be in the base to encourage wider use. I agree. Thanks again for your help. Brian --- Date: Wed, 12 Nov 2003 10:05:39 -0500 From: Brian Beckage [EMAIL PROTECTED] To: [EMAIL PROTECTED] Subject: [R] Chron, as.POSIXct problem Dear R list, I noticed the following 'problem' when changing the format of dates created with seq.dates() (from the Chron library) using as.POSIXct() (R 1.8.0 on OSX 10.2.8): datesTest-seq.dates(from=10/01/1952, length=3, by=days); datesTest [1] 10/01/52 10/02/52 10/03/52 # Now changing the format to show year as 1952. datesTest-format(as.POSIXct(datesTest), %m/%d/%Y) datesTest [1] 09/30/1952 10/01/1952 10/02/1952 The dates were shifted by one day. The work around is simple enough, e.g., datesTest-format(as.POSIXct(datesTest+1), %m/%d/%Y) [1] 10/01/1952 10/02/1952 10/03/1952 but I wonder if this is the intended behavior? Brian __ [EMAIL PROTECTED] mailing list https://www.stat.math.ethz.ch/mailman/listinfo/r-help ___ No banners. No pop-ups. No kidding. Introducing My Way - http://www.myway.com __ [EMAIL PROTECTED] mailing list https://www.stat.math.ethz.ch/mailman/listinfo/r-help
