Thanks Jeff and Spencer, I will probably set the time zone for my session, but
I had forgotten the possibility of setting the time zone attribute of a POSIXct
object, which would have solved my problem also.
Denis
Le 2011-06-05 à 11:14, Spencer Graves a écrit :
> 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.
>> ---------------------------------------------------------------------------
>> Jeff Newmiller The ..... ..... Go Live...
>> DCN:<jdnew...@dcn.davis.ca.us> Basics: ##.#. ##.#. Live Go...
>> Live: OO#.. Dead: OO#.. Playing
>> Research Engineer (Solar/Batteries O.O#. #.O#. with
>> /Software/Embedded Controllers) .OO#. .OO#. rocks...1k
>> ---------------------------------------------------------------------------
>> Sent from my phone. Please excuse my brevity.
>>
>> 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
>> _____________________________________________
>>
>> 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.
>>
>>
>> [[alternative HTML version deleted]]
>>
>> ______________________________________________
>> R-help@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.
>>
>
>
> --
> 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
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