[R] as.POSIXct problem?

[ripley@stats.ox.ac.uk]

On Thu, 2 Jan 2003, Frank E Harrell Jr wrote:

> Under
>
> platform i686-pc-linux-gnu
> arch     i686
> os       linux-gnu
> system   i686, linux-gnu
> status
> major    1
> minor    6.1
> year     2002
> month    11
> day      01
> language R
>
> > x <- strptime(c('10/10/1969','12/31/2002'),format='%m/%d/%Y')
> > x
> [1] "1969-10-10" "2002-12-31"
> > as.POSIXct(x)
> [1] NA               "2002-12-31 EST"
>
> Why the NA?  If this is not the preferred way to convert a character
string to POSIXct what is?

It's a function of your system, which is telling you that is an invalid
*time* (it is midnight, BTW). I get

> as.POSIXct(x)
[1] "1969-10-10 GMT" "2002-12-31 GMT"

Did by any chance your locale change time zones that day?  Trying giving a
valid time as well.

> On a more minor note why the EST if no time is printed?

Because it has to be in some time zone, and it uses the current one if you
did not specify it (there is a tz argument, and it is described on the
help page!).  As far as I can see from your email headers you are in EST.


-- 
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)
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