On 6/5/2011 9:30 AM, Jeff Newmiller wrote:
Sys.setenv(TZ="Etc/GMT+5")
Or:
x <- as.POSIXct(as.Date('2011-01-15'))
attr(x, 'tzone') <- "Etc/GMT+5"
x
This version works without Sys.setenv, which may not work on some
platforms. Unfortunately, I believe there are some copy operations that
lose attributes like tzone, so you need to check.
For some of the most advanced and complicated time series
problems, you might consider what's available from the Rmetrics project,
e.g., at "https://www.rmetrics.org/ebooks": They are designed to deal
with coordinating trading data from financial markets all over the
world, each of which affects all the others but have different trading
hours.
Hope this helps.
Spencer
Make the timezone you prefer the default for that R session.
FWIW: EST may or may not exist as a valid timezone on your system, but it is an
ambiguous notation anyway.
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Denis Chabot<chabot.de...@gmail.com> wrote:
Hi,
For a project I try to keep everything in normal time, not daylight saving
time, to prevent problem when instruments collected data during the nights when
we go from DST to normal time.
But sometimes R tricks me and I do not know how to prevent it.
This is one example:
lights_on = as.POSIXct(c("2011-05-06 04:09:26", "2011-05-07 04:07:53", "2011-05-08
04:06:21",
"2011-05-09 04:04:51", "2011-05-10 04:03:22", "2011-05-11 04:01:55",
"2011-05-12 04:00:30", "2011-05-13 03:59:06", "2011-05-14 03:57:45",
"2011-05-15 03:56:25", "2011-05-16 03:55:07"), tz="EST") # not DST
lights_off = as.POSIXct(c("2011-05-05 18:56:54", "2011-05-06 18:58:19", "2011-05-07
18:59:44",
"2011-05-08 19:01:08", "2011-05-09 19:02:32", "2011-05-10 19:03:55",
"2011-05-11 19:05:18", "2011-05-12 19:06:40", "2011-05-13 19:08:01",
"2011-05-14 19:09:22", "2011-05-15 19:10:42" ), tz="EST") # not DST
(a = lights_on[c(1,5)]) # not DST
[1] "2011-05-06 04:09:26 EST" "2011-05-10 04:03:22 EST"
(b = lights_off[c(2,6)]) # not DST
[1] "2011-05-06 18:58:19 EST" "2011-05-10 19:03:55 EST"
(x = c(lights_off[2], lights_on[2])) # suddenly DST
[1] "2011-05-06 19:58:19 EDT" "2011-05-07 05:07:53 EDT"
Why did x end up in DST? How could I prevent it?
Thanks in advance,
Denis
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PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
and provide commented, minimal, self-contained, reproducible code.
--
Spencer Graves, PE, PhD
President and Chief Operating Officer
Structure Inspection and Monitoring, Inc.
751 Emerson Ct.
San José, CA 95126
ph: 408-655-4567
______________________________________________
R-help@r-project.org mailing list
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PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
and provide commented, minimal, self-contained, reproducible code.
