R help - May 2010 - Strange behaviour when using diff with POSIXt and POSIXlt objects

Dear list,

I´m calculating time differences between series of time stamps and I noticed
something odd:

If I do this...
> time1=strptime("2009 05 31 22 57 00",format="%Y %m %d %H
%M")
> time2=strptime("2009 05 31 23 07 00",format="%Y %m %d %H
%M")
>
> diff(c(time1,time2),units="mins")
Time difference of 10 mins

.. I get the correct response in minutes.  But if I try the same thing with
different values, say..
> time3=strptime("2009 06 01 00 47 00",format="%Y %m %d %H
%M")
> time4=strptime("2009 06 01 00 57 00",format="%Y %m %d %H
%M")
>
> diff(c(time3,time4))
Time difference of NA secs

...which is not what I´m looking for. The difference should also be 10
minutes.

I burned a few neurons (and searched the documentation) and I cannot figure
why this happens.  Any ideas?

All the best,

Julian

Julian Mariano Burgos
Hafrannsóknastofnunin/Marine Research Institute
Skúlagata 4, 121 Reykjavík, Iceland
Sími/Telephone : +354-5752037
Bréfsími/Telefax:  +354-5752001
Netfang/Email: julian@hafro.is, jmburgos@uw.edu

	[[alternative HTML version deleted]]

Please provide information as to what version you are using;  works fine for me:
> time3=strptime("2009 06 01 00 47 00",format="%Y %m %d %H
%M")
> time4=strptime("2009 06 01 00 57 00",format="%Y %m %d %H
%M")
>
> diff(c(time3,time4))
Time difference of 10 mins
>
I have version 2.10.1

On Thu, May 20, 2010 at 12:36 PM, Julian Burgos <jmburgos at uw.edu>
wrote:
> Dear list,
>
> I?m calculating time differences between series of time stamps and I
noticed
> something odd:
>
> If I do this...
>
>> time1=strptime("2009 05 31 22 57 00",format="%Y %m %d %H
%M")
>> time2=strptime("2009 05 31 23 07 00",format="%Y %m %d %H
%M")
>>
>> diff(c(time1,time2),units="mins")
> Time difference of 10 mins
>
> .. I get the correct response in minutes. ?But if I try the same thing with
> different values, say..
>
>> time3=strptime("2009 06 01 00 47 00",format="%Y %m %d %H
%M")
>> time4=strptime("2009 06 01 00 57 00",format="%Y %m %d %H
%M")
>>
>> diff(c(time3,time4))
> Time difference of NA secs
>
> ...which is not what I?m looking for. The difference should also be 10
> minutes.
>
> I burned a few neurons (and searched the documentation) and I cannot figure
> why this happens. ?Any ideas?
>
> All the best,
>
> Julian
>
> Julian Mariano Burgos
> Hafranns?knastofnunin/Marine Research Institute
> Sk?lagata 4, 121 Reykjav?k, Iceland
> S?mi/Telephone : +354-5752037
> Br?fs?mi/Telefax: ?+354-5752001
> Netfang/Email: julian at hafro.is, jmburgos at uw.edu
>
> ? ? ? ?[[alternative HTML version deleted]]
>
>
> ______________________________________________
> 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.
>
>


-- 
Jim Holtman
Cincinnati, OH
+1 513 646 9390

What is the problem that you are trying to solve?