similar to: Unexpected behavior of clocktime related to daylight savings time

Colleagues, I just encountered some unexpected behavior of difftime in relationship to the change from daylight savings to standard time. My understanding is that DST and ST take effect at 2AM. However, the code below suggests that R (version 2.8.0 in OS X) implements the change at 2:16AM: Expected: > > difftime("2008-11-02 02:01:00", "2008-11-02 00:59:00")

Dear All, The recent improvement in RODBC to recognize datetimes in tables has exposed my ongoing confusion. All my data are obtained from a satellite system (Argos) which tags events in the GMT time zone. Daylight saving is ignored. To my way of thinking this means that 1. twelve-o-clock means halfway through the day regardless of season, and 2. the difftime of any two dates where

Running under Windows XP 64 bit, as.POSIXlt()/as.POSIXct() seem to think that US time zones (EST5EDT, MST7MDT) switched from daylight savings back to standard time on Oct 28, 2007, whereas the switch is actually on Sun Nov 04, 2007. Examples: > Sys.timezone() [1] "Mountain Daylight Time" > as.POSIXct("2007-10-30 12:38:47") [1] "2007-10-30 12:38:47 Mountain

Hello, Suppose we need a function that takes a POSIXct object and need to calculate the time difference between it and GMT time: gmtDiff <- function(time) { time.gmt <- as.POSIXct(format(time, tz="GMT")) time.plt <- as.POSIXlt(time) dlstime <- ifelse(time.plt$isdst > 0, 1, 0) timezone <- as.numeric(difftime(time, time.gmt, units="hours"))

There is incompatibility between R strptime and musl libc. I posted about it on their mailing list, but they need more information I can't provide, so I'm forwarding the message here in hope R developers can help. Thanks. ---------- Forwarded message ---------- From: Rich Felker <dalias at libc.org> Date: Thu, Feb 4, 2016 at 2:07 PM Subject: Re: [musl] strptime() question To: Alba

Dear all, I have a vector generated using the function strptime: > my.dt [1] "2004-04-19 08:35:00 W. Europe Daylight Time" "2004-04-19 09:35:00 W. Europe Daylight Time" "2004-04-19 11:35:00 W. Europe Daylight Time" [4] "2004-04-19 13:35:00 W. Europe Daylight Time" "2004-04-20 07:50:00 W. Europe Daylight Time" > class(my.dt) [1]

R-listers, I have noticed several posts on issues with difftime producing NA's but they have been for older versions of R. Here's the issue associated with difftime that I am dealing with in R 2.12.2. > preciptime = strptime("01/10/2007 14:00",format="%m/%d/%Y %H:%M") > class(preciptime) [1] "POSIXlt" "POSIXt" > # Now using difftime, this

In some cases, incorrect results are produced by the code below intended to calculate the number of days between 2 dates. The year in question was a leap year. Note the results for 2004-04-04 and 2004-04-05 are the same! They should be 37 and 38 respectively. > as.integer(as.POSIXct("2004-04-02") - as.POSIXct("2004-02-27")) [1] 35 >

Hi all, I've been having some trouble with times in regards to daylight savings in R version 2.8.1. I have an ORACLE database that R is importing data in from, for the 2am and 2:30am time intervals for the dates that daylight savings starts the times are getting read as NA values into R. I'm also finding that if I open a R workspace from version 6.2.2,the datetimes are

Hi list, Could someone explain to me why the following result is not a integer? > difftime(strptime("24NOV2004", format="%d%b%Y"), strptime("13MAY2004", >format="%d%b%Y"), units="days") Time difference of 195.0417 days I'm using R2.12.0 on WinXP. Thanks! ...Tao

hi there, does anyone know how to calculate the amount of daylight on every day of the year in R? I mean the time between sunrise and sunset. thanks -- View this message in context: http://r.789695.n4.nabble.com/daylight-tp4647213.html Sent from the R help mailing list archive at Nabble.com.

I'm having difficulties with daylight saving times in US time zones. (Apologies for the long post, but the problem seems subtle and complex, unless I'm doing something completely wrong, in which case it should be evident from the first 10 lines below.) This is what I see, using a (slightly modified) example from ?as.POSIXlt : > as.POSIXlt((d <- Sys.time()), "EST5EDT") #

Hi, I''ve been trying to do timezone conversion, and have some trouble getting it to work on my Windows machine. Searching the web, I found http://wiki.rubyonrails.com/rails/pages/HowtoSetDefaultTimeZone ...which explains how to set the default timezone. I''m using an environment.rb that include the lines: ActiveRecord::Base.default_timezone = :utc ENV[''TZ''] =

I am analysing some data collected over a number of months from Allentown, PA, which is just north of Philadelphia. I am using as.POSIXct for dates and times, and I need to get the timezone specification correct. Going on the documentation for DateTimeClasses, I believe one way to specify the correct time zone is tz="EST5EDT" I would be grateful for any advice on this. I ask

I am trying to do ephemeris calculations in R, which involves calculating an elapsed time. As illustrated below, difftime seems to have problems with my method, since the fractional day is sometimes the correct 0.5 and sometimes the incorrect 0.46. I am doing this on with R-2.6.1 on a powerpc-apple-darwin8.10.1 system. I get the same results for as.POSIXlt() instead of as.POSIXct(), but the

Anybody have an idea why I would get a non-integer value for the number of days here? > difftime('2004-08-05','2001-01-03',units='days') Time difference of 1309.958 days Would you just round off? Best, Jon

I have a problem with results from difftime being 1 hour different than expected. 2 examples are given below: datetime <- matrix(data=rbind(c("2012-03-31 21:00:00", "2012-04-01 00:00:00", "2012-04-01 03:00:00", "2012-04-01 06:00:00"), c("2012-10-06 21:00:00", "2012-10-07 00:00:00", "2012-10-07 03:00:00",

Hello all, I am manipulating a large database with 70,000 records. "strptime" generates a date variable but R treats some of the values as NA. I attach a simple example below. I have spent hours on this problem. Any hint would be greatly appreciated. Many thanks, Edwin Sun # =======start of sample code ============= > x <- c("2005-04-02 19:03:00", "2005-04-03

I have a data frame that contains dates, but when I use as.POSIXlt() I lose the hours on all records. I traced this down to a particuar hour which causes the issue... > as.POSIXlt('2004-10-31 02:00:00') [1] "2004-10-31" > as.POSIXlt('2004-10-31 03:00:00') [1] "2004-10-31 03:00:00" How do I tell as.POSIXlt() to ignore daylight savings and just convert to

Colleagues I am executing a length script in R (20K lines). At one point, it returns: > Loading required package: tcltk > Loading Tcl/Tk interface ... done > Loading required package: Hmisc > Loading required package: survival > Loading required package: stats > Loading required package: graphics > Loading required package: splines > Attaching package: 'Hmisc'