[R] Unable to understand strptime() behaviour

[Prof Brian Ripley]

The result of strptime is a 9-element list.  From the help page

Value:

      'strptime' turns character representations into an object of class
      '"POSIXlt"'.

See Also:

      DateTimeClasses for details of the date-time classes; 'locales' to
      query or set a locale.

Try ?DateTimeClasses.


On Wed, 1 Dec 2004, Tim Churches wrote:

> R V2.0.1 on Windows XP.
>
> I have read the help pages on strptime() over and over, but can't
> understand why strptime() is producing the following results.
>
>  > v <- format("2002-11-31", format="%Y-%m-%d")
>  > v
> [1] "2002-11-31"
>  > factor(v, levels=v)
> [1] 2002-11-31
> Levels: 2002-11-31
>  > x <- strptime("2002-11-31", format="%Y-%m-%d")
>  > x
> [1] "2002-12-01"
>  > factor(x, levels=x)
> [1] <NA> <NA> <NA> <NA> <NA> <NA> <NA> <NA> <NA>
> Levels: 2002-12-01 NA NA NA NA NA NA NA NA

I can't understand why you are trying to turn a classed object into a 
factor.

-- 
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