[R] strange date problem - May 3, 1992 is NA

[Brian Diggs]

On 6/22/2011 12:09 PM, Luke Miller wrote:
> For what it's worth, I cannot reproduce this problem under a nearly
> identical instance of R (R 2.12.1, Win 7 Pro 64-bit). I also can't
> reproduce the problem with R 2.13.0. You've got something truly weird
> going on with your particular instance of R.
>
>
>> is.na(strptime("5/3/1992", format="%m/%d/%Y"))
> [1] FALSE
>> 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
>
> other attached packages:
> [1] rj_0.5.2-1      lattice_0.19-17
>
> loaded via a namespace (and not attached):
> [1] grid_2.12.1  rJava_0.8-8  tools_2.12.1

Like Luke, I can not reproduce what you see in (an old installation of) 
R 2.12.1 (and it also didn't have rj, lattice, grid, rJava, or tools 
attached or loaded in any way).

My vague gut feeling is it might be a timezone/daylight savings time 
related issue (though usually times have to be involved).  At least, 
that is a common problem with weird things happening with dates.

What do you get as output for the following?

Sys.timezone()
Sys.info()
conflicts()
dput(strptime("5/3/1992", format="%m/%d/%Y"))
dput(as.POSIXct(strptime("5/3/1992", format="%m/%d/%Y")))
dput(strptime("5/2/1992", format="%m/%d/%Y"))
dput(as.POSIXct(strptime("5/2/1992", format="%m/%d/%Y")))


> On Wed, Jun 22, 2011 at 2:40 PM, Alexander Shenkin<ashenkin at ufl.edu>  wrote:
>> On 6/22/2011 1:34 PM, Sarah Goslee wrote:
>>> On Wed, Jun 22, 2011 at 2:28 PM, David Winsemius<dwinsemius at 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<ashenkin at 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 at 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.
>>
>
>
>


-- 
Brian S. Diggs, PhD
Senior Research Associate, Department of Surgery
Oregon Health & Science University