similar to: Enhancement suggestion: POSIXt0

The problem with POSIXt is that you must consider timezones and daylight vs. standard time issues even if you don't want to. This violates modularity (viz. your routines becomes coupled to unrelated information) and leads to subtle errors where different routines are assuming different time zones. The problem is that the time, date, day of the week, month, etc. of a date depend on its

The following code: cut(as.POSIXct("2009-11-01 04:00:00", tz="America/Los_Angeles"), "1 day") gives the error: Error in seq.int(0, to - from, by) : 'to' must be finite This is related to November 1st, 2009 being the switchover date from daylight savings time to standard time in the America/Los_Angeles time zone. In particular, in cut.POSIXt, the starting

I have asked this question before, and received some suggestions for work-arounds that get the job done--and they are much appreciated. But I would still like to find out if I'm missing something, and whether there is a direct way using POSIXt functions (as.POSIXct, as.POSIXlt, strptime, in particular). I have environmental data collected once per minute. Here is a subset of 3 input

I have found what looks like a small problem in trunc.POSIXt() involving the transition to/from standard time and daylight savings time. Assuming my assessment is correct, I have a potential solution to offer. If a time in daylight savings time is rounded such that the rounded value is on the other side of the transition, the isdst element does not get changed accordingly. I have tested only

This is not a bug in R: the documentation does say the result is OS-specific. `GMT' is a not a proper timezone on Windows, so NA is a valid answer. (Windows seems to use GMT to refer to the timezone of the UK, e.g. > Sys.time() [1] "2005-07-11 07:49:56 GMT Daylight Time" > Sys.timezone() [1] "GMT Daylight Time" although I am in British Summer Time not GMT.)

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]

It looks like a timezone issue, and it's causing confusion to me at least. My original data: gmt <- c("19880101 0000", "19880101 0100", "19880101 0300", "19880101 0400", "19880101 0500", "19880101 0600") These were converted to local dates/times with akst<-strptime(gmt,format="%Y%m%d %H%M")-(3600*9) # because I want

> On 18 May 2017, at 14:51, peter dalgaard <pdalgd at gmail.com> wrote: > > >> On 18 May 2017, at 13:47 , Joris Meys <jorismeys at gmail.com> wrote: >> >> Correction: Also dlt uses the default timezone, but POSIXlt is not recalculated whereas POSIXct is. Reason for that is the different way values are stored (hours, minutes, seconds as opposed to minutes

I am still experiencing problems with seq.POSIXt() missing off the last day of the series: > seq(as.POSIXct("2004-03-25"),as.POSIXct("2004-03-31"),by="DSTdays") [1] "2004-03-25 GMT Standard Time" "2004-03-26 GMT Standard Time" "2004-03-27 GMT Standard Time" [4] "2004-03-28 GMT Standard Time" "2004-03-29 GMT Daylight

> On 18 May 2017, at 14:58 , Martyn Plummer <plummerM at iarc.fr> wrote: > > > >> On 18 May 2017, at 14:51, peter dalgaard <pdalgd at gmail.com> wrote: >> >> >>> On 18 May 2017, at 13:47 , Joris Meys <jorismeys at gmail.com> wrote: >>> >>> Correction: Also dlt uses the default timezone, but POSIXlt is not recalculated

Correction: Also dlt uses the default timezone, but POSIXlt is not recalculated whereas POSIXct is. Reason for that is the different way values are stored (hours, minutes, seconds as opposed to minutes from origin, as explained in my previous mail) CHeers Joris On Thu, May 18, 2017 at 1:45 PM, Joris Meys <jorismeys at gmail.com> wrote: > This has to do with your own timezone. If I run

Hi, I have a casting/formatting question on hist.POSIXt: The histogram plot from POSIXct works perfect (with help of Prof. Ripley -thanks!). When processing the hist(plot=FALSE) output and then plotting the results over the x-axis (bins) coming from hist(), I lose the date/time labels, getting instead integers displayed. Trying to cast the $breaks with as.POSIXct gives silly results with

I have two data frames, with two columns each, the first being a Date variable. I would like to convert them to xts objects, indexed by the Date column. I would like to use as.Date and not as.POSIXct as the dateformat. The puzzling fact is that it works for the first one but not the other. Here is a screenshot of the error: > str(DF1) 'data.frame': 367 obs. of 2 variables: $

tplate at acm.org wrote: > 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. > > =20 Not Our Problem. (This sort of thing never is. We are wholly dependent=20 on the OS for this information).

This has to do with your own timezone. If I run that code on my computer, both formats are correct. If I do this after Sys.setenv(TZ = "UTC") Then: > cbind(format(dlt), format(dct)) [,1] [,2] [1,] "2016-12-06 21:45:41" "2016-12-06 20:45:41" [2,] "2016-12-06 21:45:42" "2016-12-06 20:45:42" The reason for that, is that

?Hi again, I take advantage of my previous mail to ask you a question for which I was looking for an answer when detected the behaviour I previously told. In the help of DataTimeClasses one can read: "POSIXlt" objects will often have an attribute "tzone", a character vector of length 3 giving the time zone name from the TZ environment variable and the names of the base time

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") #

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

Hi, One of the big decisions when writing code is how to handle dates and times. Gabor Grothendieck provided an excellent overview of the issue in his R News 4/1 (2004) article, and many users and developers are probably using it as a guide. The proposed guideline is to use the simplest class required; as Gabor put it "use Date if possible, otherwise use chron, and otherwise use

> On 18 May 2017, at 13:47 , Joris Meys <jorismeys at gmail.com> wrote: > > Correction: Also dlt uses the default timezone, but POSIXlt is not recalculated whereas POSIXct is. Reason for that is the different way values are stored (hours, minutes, seconds as opposed to minutes from origin, as explained in my previous mail) > I would suspect that there is something more subtle