I can reproduce your problem when using a time that doesn't exist because it is between 2am and 3am on the Sunday that we switch from winter time to summer time:
> z <- strptime(paste(paste(sep="/", 4, 5, 1992), "2:30"), format="%m/%d/%Y %H:%M") > z [1] "1992-04-05 02:30:00" > is.na(z) [1] TRUE > str(unclass(z)) List of 9 $ sec : num 0 $ min : int 30 $ hour : int 2 $ mday : int 5 $ mon : int 3 $ year : int 92 $ wday : int 0 $ yday : int 95 $ isdst: int -1 Perhaps your time zone description file has the time changing around midnight on May 3, 1992. Bill Dunlap Spotfire, TIBCO Software wdunlap tibco.com > -----Original Message----- > From: r-help-boun...@r-project.org > [mailto:r-help-boun...@r-project.org] On Behalf Of William Dunlap > Sent: Wednesday, June 22, 2011 1:23 PM > To: Alexander Shenkin; r-help@r-project.org > Subject: Re: [R] strange date problem - May 3, 1992 is NA > > The isdst value -1 doesn't seem right. Shouldn't it > be either 0 (not daylight savings time) or 1 (yes dst)? > I've only seen isdst==-1 when all the other entries > were NA (that happens when the string doesn't match > the format). > > In the parts of the US where daylight savings time is > used the switchover took place near the beginning of > April in 1992, so you should have isdst=1 by May 3. > Perhaps you have an odd timezone file on your machine. > > Bill Dunlap > Spotfire, TIBCO Software > wdunlap tibco.com > > > -----Original Message----- > > From: Alexander Shenkin [mailto:ashen...@ufl.edu] > > Sent: Wednesday, June 22, 2011 1:07 PM > > To: William Dunlap > > Subject: Re: [R] strange date problem - May 3, 1992 is NA > > > > Hi Bill, > > > > Thanks for your reply. The results look almost identical > to my eyes, > > except for the mysterious "TRUE"... > > > > > methods("is.na") > > [1] is.na.data.frame is.na.numeric_version is.na.POSIXlt > > > trace(methods("is.na"), quote(cat(" is.na: class(x)=", > > class(x), "\n"))) > > Tracing function "is.na.data.frame" in package "base" > > Tracing function "is.na.numeric_version" in package "base" > > Tracing function "is.na.POSIXlt" in package "base" > > [1] "is.na.data.frame" "is.na.numeric_version" "is.na.POSIXlt" > > > z <- strptime("5/3/1992", format="%m/%d/%Y") > > > is.na(z) > > Tracing is.na.POSIXlt(z) on entry > > is.na: class(x)= POSIXlt POSIXt > > [1] TRUE > > > str(unclass(z)) > > List of 9 > > $ sec : num 0 > > $ min : int 0 > > $ hour : int 0 > > $ mday : int 3 > > $ mon : int 4 > > $ year : int 92 > > $ wday : int 0 > > $ yday : int 123 > > $ isdst: int -1 > > > > > > > sessionInfo() > > R version 2.12.1 (2010-12-16) > > Platform: i386-pc-mingw32/i386 (32-bit) > > > > locale: > > [1] LC_COLLATE=English_United States.1252 > > [2] LC_CTYPE=English_United States.1252 > > [3] LC_MONETARY=English_United States.1252 > > [4] LC_NUMERIC=C > > [5] LC_TIME=English_United States.1252 > > > > attached base packages: > > [1] stats graphics grDevices utils datasets methods base > > > > loaded via a namespace (and not attached): > > [1] tools_2.12.1 > > > > thanks, > > allie > > > > On 6/22/2011 1:50 PM, William Dunlap wrote: > > > What do you get for the following commands, which > > > show which is.na method is getting called and > > > the internal structure of the dataset made > > > by strptime? > > > > > >> methods("is.na") > > > [1] is.na.data.frame is.na.numeric_version is.na.POSIXlt > > >> trace(methods("is.na"), quote(cat(" is.na: class(x)=", class(x), > > > "\n"))) > > > Tracing function "is.na.data.frame" in package "base" > > > Tracing function "is.na.numeric_version" in package "base" > > > Tracing function "is.na.POSIXlt" in package "base" > > > [1] "is.na.data.frame" "is.na.numeric_version" > "is.na.POSIXlt" > > >> z <- strptime("5/3/1992", format="%m/%d/%Y") > > >> is.na(z) > > > Tracing is.na.POSIXlt(z) on entry > > > is.na: class(x)= POSIXlt POSIXt > > > [1] FALSE > > >> str(unclass(z)) > > > List of 9 > > > $ sec : num 0 > > > $ min : int 0 > > > $ hour : int 0 > > > $ mday : int 3 > > > $ mon : int 4 > > > $ year : int 92 > > > $ wday : int 0 > > > $ yday : int 123 > > > $ isdst: int 1 > > > > > > > > > > > > Bill Dunlap > > > Spotfire, TIBCO Software > > > wdunlap tibco.com > > > > > >> -----Original Message----- > > >> From: r-help-boun...@r-project.org > > >> [mailto:r-help-boun...@r-project.org] On Behalf Of > > Alexander Shenkin > > >> Sent: Wednesday, June 22, 2011 11:41 AM > > >> To: Sarah Goslee; r-help@r-project.org > > >> Subject: Re: [R] strange date problem - May 3, 1992 is NA > > >> > > >> On 6/22/2011 1:34 PM, Sarah Goslee wrote: > > >>> On Wed, Jun 22, 2011 at 2:28 PM, David Winsemius > > >> <dwinsem...@comcast.net> wrote: > > >>>> > > >>>> On Jun 22, 2011, at 2:03 PM, Sarah Goslee wrote: > > >>>> > > >>>>> Hi, > > >>>>> > > >>>>> On Wed, Jun 22, 2011 at 11:40 AM, Alexander Shenkin > > >> <ashen...@ufl.edu> > > >>>>> wrote: > > >>>>>>> > > >>>>>>> is.na(strptime("5/2/1992", format="%m/%d/%Y")) > > >>>>>> > > >>>>>> [1] FALSE > > >>>>>>> > > >>>>>>> is.na(strptime("5/3/1992", format="%m/%d/%Y")) > > >>>>>> > > >>>>>> [1] TRUE > > >>>>> > > >>>>> I can't reproduce your problem on R 2.13.0 on linux: > > >>>> > > >>>> I also cannot reproduce it on a Mac with 2.13.0 beta > > >>> > > >>> Which strongly suggests that you should start by > upgrading your R > > >>> installation if at all possible. > > >>> > > >>> I'd also recommend trying it on a default R session, > with no extra > > >>> packages loaded, and no items in your workspace. It's > > possible that > > >>> something else is interfering. > > >>> > > >>> On linux, that's achieved by typing R --vanilla at the > > command line. > > >>> I'm afraid I don't know how to do it for Windows, but should be > > >>> similarly straightforward. > > >>> > > >> Thanks Sarah. Still getting the problem. I should surely > > >> upgrade, but > > >> still, not a bad idea to get to the bottom of this, or at > > >> least have it > > >> documented as a known issue. BTW, I'm on Windows 7 Pro x64. > > >> > > >> (running Rgui.exe --vanilla): > > >> > > >>> is.na(strptime("5/3/1992", format="%m/%d/%Y")) > > >> [1] TRUE > > >> > > >>> is.na(strptime("5/2/1992", format="%m/%d/%Y")) > > >> [1] FALSE > > >> > > >>> sessionInfo() > > >> R version 2.12.1 (2010-12-16) > > >> Platform: i386-pc-mingw32/i386 (32-bit) > > >> > > >> locale: > > >> [1] LC_COLLATE=English_United States.1252 > > >> [2] LC_CTYPE=English_United States.1252 > > >> [3] LC_MONETARY=English_United States.1252 > > >> [4] LC_NUMERIC=C > > >> [5] LC_TIME=English_United States.1252 > > >> > > >> attached base packages: > > >> [1] stats graphics grDevices utils datasets > > methods base > > >> > > >> ______________________________________________ > > >> R-help@r-project.org mailing list > > >> https://stat.ethz.ch/mailman/listinfo/r-help > > >> PLEASE do read the posting guide > > >> http://www.R-project.org/posting-guide.html > > >> and provide commented, minimal, self-contained, > reproducible code. > > >> > > > > ______________________________________________ > R-help@r-project.org mailing list > https://stat.ethz.ch/mailman/listinfo/r-help > PLEASE do read the posting guide > http://www.R-project.org/posting-guide.html > and provide commented, minimal, self-contained, reproducible code. > ______________________________________________ R-help@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.
