R help - Sep 2011 - Problems with as.POSIXct

Hi R users:

This is a very strange problem:

Why this instruction shows me NA?, 
and any other date shows me that error!

as.POSIXct(strptime("1992-5-3",format="%Y-%m-%d"))

This is my R version on windows 7.
"R version 2.13.1 Patched (2011-08-25 r56794)"

Thank you for your help.

Didn't Columbia switch to a year of daylight
savings time at what would have been midnight
May 3, 1992 (so midnight did not exist that day)?

Bill Dunlap
Spotfire, TIBCO Software
wdunlap tibco.com 
> -----Original Message-----
> From: r-help-bounces at r-project.org [mailto:r-help-bounces at
r-project.org] On Behalf Of KENNETH R
> CABRERA
> Sent: Thursday, September 22, 2011 8:59 AM
> To: r-help at r-project.org
> Cc: krcabrer at gmail.com
> Subject: [R] Problems with as.POSIXct
> 
> Hi R users:
> 
> This is a very strange problem:
> 
> Why this instruction shows me NA?,
> and any other date shows me that error!
> 
> as.POSIXct(strptime("1992-5-3",format="%Y-%m-%d"))
> 
> This is my R version on windows 7.
> "R version 2.13.1 Patched (2011-08-25 r56794)"
> 
> Thank you for your help.
> 
> ______________________________________________
> 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.

What timezone is this?

In America/Bogota there was no midnight that day, so the time would be 
invalid.  The Olson database has

# Colombia
# Rule  NAME    FROM    TO      TYPE    IN      ON      AT      SAVE    LETTER/S
Rule    CO      1992    only    -       May      3      0:00    1:00    S
Rule    CO      1993    only    -       Apr      4      0:00    0 
-
# Zone  NAME            GMTOFF  RULES   FORMAT  [UNTIL]
Zone    America/Bogota  -4:56:20 -      LMT     1884 Mar 13
                         -4:56:20 -      BMT     1914 Nov 23 # Bogota Mean Time
                         -5:00   CO      CO%sT   # Colombia Time

When all else fails, read the help:

      Character input is first converted to class ?"POSIXlt"? by
      ?strptime?: numeric input is first converted to ?"POSIXct"?. 
Any
      conversion that needs to go between the two date-time classes
      requires a timezone: conversion from ?"POSIXlt"? to
?"POSIXct"?
      will validate times in the selected timezone.  One issue is what
      happens at transitions to and from DST, for example in the UK

      as.POSIXct(strptime('2011-03-27 01:30:00', '%Y-%m-%d
%H:%M:%S'))
      as.POSIXct(strptime('2010-10-31 01:30:00', '%Y-%m-%d
%H:%M:%S'))

      are respectively invalid (the clocks went forward at 1:00 GMT to
      2:00 BST) and ambiguous (the clocks went back at 2:00 BST to 1:00
      GMT).


On Thu, 22 Sep 2011, KENNETH R CABRERA wrote:
> Hi R users:
>
> This is a very strange problem:
>
> Why this instruction shows me NA?,
> and any other date shows me that error!
>
> as.POSIXct(strptime("1992-5-3",format="%Y-%m-%d"))
>
> This is my R version on windows 7.
> "R version 2.13.1 Patched (2011-08-25 r56794)"
>
> Thank you for your help.
>
> ______________________________________________
> 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 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