[R] strptime "March 14 2010" and NA?

[Prof Brian Ripley]

On Tue, 8 Feb 2011, Manuel Gimond wrote:

> Converting date strings that range between Mar-14-2010 2:00 and
> Mar-14-2010 2:59 (inclusive) to date objects (POSIX) returns a NA entity:
>
> > strptime("3/14/2010 2:00",format="%m/%d/%Y %H:%M")
> [1] "2010-03-14 02:00:00"
>
> This looks fine, however other functions such as plot see a NA object
> instead:
>
> > is.na(strptime("3/14/2010 2:00",format="%m/%d/%Y %H:%M"))
> [1] TRUE
>
> I've processed an entire range of dates for 2010 and have only come
> across this problem for the aforementioned date ranges. For instance,
> the following dates work fine:
>
> > is.na(strptime("3/14/2010 3:00",format="%m/%d/%Y %H:%M"))
> [1] FALSE
>
> > is.na(strptime("10/14/2010 23:00",format="%m/%d/%Y %H:%M"))
> [1] FALSE
>
> which is what I would expect for ALL dates.
>
> Could this be a bug with POSIX or strptime? I'm running R x64 2.12.0 on Win7

You haven't told us your timezone, but very likely you are in one 
where that hour did not actually exist (as DST came into effect).

> 	[[alternative HTML version deleted]]

And you definitely overlooked the request in the posting guide not to 
send HTML.

>
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-- 
Brian D. Ripley,                  ripley at stats.ox.ac.uk
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, UK                Fax:  +44 1865 272595