On Mar 10, 2011, at 11:17 AM, Daniel Nüst wrote:
Hello!
I've been trying to get this right for quite a while now and fear
there is an easy solution I just don't see. I did not have this
problem in Linux, and I searched r-help and Google but did not find a
solution, but of course I am grateful for and resources I might not
have found our not understood yet.
I try to parse a time stamp with time zone. I essentially just want to
parse the time stamp "1995-05-25T15:30:00+10:00" and output it exactly
like it is, using the POSIX classes (or is that impossible?).
Does this work?
as.POSIXlt(gsub("T.*(\\+|\\-)..(:)", "", # get rid of the colon in the
tz
# but preserve the sign for the %z format string
gsub("T", " ", "1995-05-25T15:30:00-1000")), # replace the
"T" with a space
format="%Y-%m-%d %H:%M:%S%z")
Please find the script and output/comments below.
Regards,
Daniel
sessionInfo()
R version 2.12.1 (2010-12-16)
Platform: x86_64-pc-mingw32/x64 (64-bit)
locale:
[1] LC_COLLATE=German_Germany.1252 LC_CTYPE=German_Germany.1252
[3] LC_MONETARY=German_Germany.1252 LC_NUMERIC=C
[5] LC_TIME=German_Germany.1252
attached base packages:
[1] stats graphics grDevices utils datasets methods base
other attached packages:
[1] rj_0.5.2-1
loaded via a namespace (and not attached):
[1] rJava_0.8-8 tools_2.12.1
t1 <- strptime("1995-05-25T15:30:00+10:00", format = "%Y-%m-%dT%H:
%M:%OS")
t2 <- strptime("1995-05-25T15:30:00+10:00", format = "%Y-%m-%dT%H:
%M:%OS%z")
strftime(t1, format = "%Y-%m-%dT%H:%M:%OS")
[1] "1995-05-25T15:30:00"
strftime(t1, format = "%Y-%m-%dT%H:%M:%OS%z")
[1] "1995-05-25T15:30:00Mitteleuropäische Sommerzeit"
# Ends in "Mitteleuropäische Sommerzeit", not in +10:00, so time
zone is ignored!
# Also no difference beetween %z and %z !
strftime(t1, format = "%Y-%m-%dT%H:%M:%OS%Z")
[1] "1995-05-25T15:30:00Mitteleuropäische Sommerzeit"
# All this does NOT remove the "Mitteleuropäische Zeit" from the
strftime output!!
# Can locale solve the problem?
Sys.getlocale(category = "LC_TIME")
[1] "German_Germany.1252"
Sys.setlocale("LC_TIME", "English")
[1] "English_United States.1252"
strftime(t1, format = "%Y-%m-%dT%H:%M:%OS%z")
[1] "1995-05-25T15:30:00Mitteleuropäische Sommerzeit"
# [1] "1995-05-25T15:30:00Mitteleuropäische Sommerzeit" -- No change.
# does t1 actually have time zone?
attributes(t1)
$names
[1] "sec" "min" "hour" "mday" "mon" "year" "wday" "yday"
"isdst"
$class
[1] "POSIXlt" "POSIXt"
format(t1, format = "%Y-%m-%dT%H:%M:%OS%z") # usetz = TRUE) # no
change on usetz
[1] "1995-05-25T15:30:00Mitteleuropäische Sommerzeit"
# Is the : in offset the problem?
t3 <- strptime("1995-05-25T15:30:00+1000", format = "%Y-%m-%dT%H:%M:
%S%z")
attributes(t3)
$names
[1] "sec" "min" "hour" "mday" "mon" "year" "wday" "yday"
"isdst"
$class
[1] "POSIXlt" "POSIXt"
format(t3, format = "%Y-%m-%dT%H:%M:%OS%z")
[1] "1995-05-25T07:30:00Mitteleuropäische Sommerzeit"
# [1] "1995-05-25T07:30:00Mitteleuropäische Sommerzeit"
strftime(t1, format = "%Y-%m-%dT%H:%M:%OS%z", tz = "+0200") # no
effect on setting tz
[1] "1995-05-25T15:30:00Mitteleuropäische Sommerzeit"
Sys.setenv(TZ="GMT") # no working effect on format and strftime
--
David Winsemius, MD
West Hartford, CT
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