[R] strptime problems

[Gabor Grothendieck]

Prof Brian Ripley <ripley <at> stats.ox.ac.uk> writes:

: 
: I suspect rather a locale problem which Date and chron will also have.


I don't think chron uses locales so it would likely also be a problem
with Date but not with chron.  

In this example, we change the locale to Danish and then display the first
of each of 12 months using chron and Date:

R> lct <- Sys.getlocale("LC_TIME"); Sys.setlocale("LC_TIME", "da")
[1] "Danish_Denmark.1252"

R> chron(paste(1:12,1,2004,sep="/"),out.format="M-D-Y") 
[1] Jan-01-2004 Feb-01-2004 Mar-01-2004 Apr-01-2004 May-01-2004 Jun-01-2004 
Jul-01-2004 Aug-01-2004 Sep-01-2004 Oct-01-2004 Nov-01-2004 Dec-01-2004

R> format(as.Date(.Last.value),"%B-%d-%Y")
 [1] "januar-01-2004"    "februar-01-2004"   "marts-01-2004"     "april-01-
2004"     "maj-01-2004"       "juni-01-2004"      "juli-01-2004"     
 [8] "august-01-2004"    "september-01-2004" "oktober-01-2004"   "november-01-
2004"  "december-01-2004" 

: 
: You are looking for an abbreviated month name (%b).  What language is the 
: object ccc in?  What language is your computer in?  See the example in
: ?strptime
: 
:      ## read in date info in format 'ddmmmyyyy'
:      ## This will give NA(s) in some locales; setting the C locale
:      ## as in the commented lines will overcome this on most systems.
:      ## lct <- Sys.getlocale("LC_TIME"); Sys.setlocale("LC_TIME", "C")
:      x <- c("1jan1960", "2jan1960", "31mar1960", "30jul1960")
:      z <- strptime(x, "%d%b%Y")
: 
: Looking for English abbreviations in a Norwegian file, for example, will 
: not work and give NAs.
: 
: On Fri, 3 Sep 2004, Thomas Petzoldt wrote:
: 
: > Per Wiklund wrote:
: > 
: >  >
: >  > Hi, I'm experiencing a problem with strptime. (R 1.9.1 on a Win2000
: >  > machine)
: > 
: > [...]
: > 
: >  > strptime(as.character(ccc[[11]]$TradeDateTime[161522]),
: >  >    "%d-%b-%y:%H:%M:%S")
: >  > [1] NA
: > 
: > [...]
: > 
: > Hello,
: > 
: > unfortunately, your code does not show what data are in the object ccc, 
: > so an exact diagnosis is almost impossible. However, I suspect you have 
: > timezone problems which are common on Windows computers. If you don't 
: > need timezone calculations I suggest to use the Date class (uppercase 
: > "D") or the chron package instead of the POSIX classes, see the last 
: > issue of R-News:
: > 
: > http://cran.r-project.org/doc/Rnews/Rnews_2004-1.pdf
: > 
: > Thomas P.
: