similar to: conversion of time

Can anyone please shed any light on why R DateTimeClasses give weird times for when daylight saving time information changes, and which aren't consistent with the OS? Example: Expected result: in New Zealand DST stopped (NZDT -> NZST) at 03:00 NZDT on 2010-04-04, as confirmed by the OS time zone info (OS X 10.8.2): zdump -v /etc/localtime /etc/localtime Sat Apr 3 13:59:59 2010 UTC

I am sorry to reply. But I need to clarify things.=0A=0AFrom searching over= the internet, I know that, before R 2.5.0, in the documentation of 'DateTi= meClasses', in 'date + x', in the explanation about 'x', there is also ment= ion that 'x' can be a 'difftime' object. Now, it has been removed.=0A=0AWhy= not doing the same in the documentation of

Hi all I am a relatively new R user so please excuse this question if it has been covered some where else, just tell me where to find it. I have a simulation model that out puts dates in a standard dd/mm/yy format R reads this as a factor and I cant find anything that will allow me to convert them to a date. In S+ I have used a chron() function that required you to specify the format of the

On the help page "DateTimeClasses {base}" it says: "One can add or subtract a number of seconds or a difftime object from a date-time object, but not add two date-time objects." However, > x<-Sys.time(); y<-Sys.time()+3600 > diff<-y-x > x; y; diff [1] "2005-11-23 19:58:20 GMT" [1] "2005-11-23 20:58:20 GMT" Time difference of 1 hours

Hello R List - I have to import Excel files (either as .csv files or using RODBC) into R (2.4.1, Windows) and operate on dates and times (e.g. find minutes between times, change dates to days of week or analyze by weeks of year). The help files for format.Date, strptime, as.POSIX, DateTimeClasses, etc. etc. are informative but perhaps a little terse. I have googled unsuccessfully for a more

What is the recommended class for time of day (independent of calendar date)? And what is the recommended way to get the time of day from a POSIXct object? (Not a string representation, but a computable representation.) I have looked in the man page for DateTimeClasses, in the Time Series Analysis Task View and in Spector's Data Manipulation book but haven't found these. Clearly I can

I have a frame which contains 3 columns: "date" "defectnum" "state" And I want to get the most recent state change for a given defect number. date is POSIXct. I have tried: aggregate(ev$date, by=list(ev$defectnum), max) Which appears to be working except that the dates seem to come back as integers (presumably the internal representation of POSIXct). When I

> (1) Create a top-level help page with a title like "Date and Time > Classes" to give a brief but general overview. This would mean the > existing DateTimeClasses would need a new title. I wanted to modify my first suggestion. Perhaps a better idea would be to reference an external document giving an overview of the subject. I couldn't find a discussion of POSIXct/POSIXlt

Hi, In short, I would like to know if there is any way to convert a numeric into a date, similar to how strptime() can convert a string to a date time class? There are some functions, etc. which don't work well with dates, and tend to force them into numerics. I understand that the number it spits back is the number of seconds since the beginning of 1970 (see the first few sentences

This is mostly a RFC [but *not* about the many extra packages, please..]: Noticing to my chagrin how my students work in a project, googling for R code and cut'n'pasting stuff together, accumulating this and that package on the way all just for simple daily time series (though with partly missing parts), using chron, zoo, lubridate, ... all for things that are very easy in base R *IF*

I know that this is correct: library(chron) x = dates("01-03-04", format="d-m-y", out.format="day mon year") print(x) It gives me the string "01 Mar 2004" which is correct. I also know that I can say: print(day.of.week(3,1,2004)) in which case he says 1, for today is monday. My question is: How do I combine these two!? :-) I have a

Times from seq.POSIXt come out wrong in AEST timezone around Feb 29 every leap year before 1970 (on Windows XP). According to help(DateTimeClasses), this is handled by "our own C code". > x <- as.POSIXct("1968-02-27") # tz="AEST" > x.gmt <- as.POSIXct("1968-02-27", tz="GMT") > data.frame( GMT=seq(x.gmt, by="day",

On the documentation page for DateTimeClasses, in the Examples section, there are the following two lines: format(.leap.seconds) # the leap seconds in your time zone print(.leap.seconds, tz = "PST8PDT") # and in Seattle's The second line (using print) seems to ignore the tz argument, and prints the dates in my time zone, while: format(.leap.seconds, tz =

Hello, ?DateTimeClasses states that "one can add or subtract a number of seconds or a 'difftime' object from a date-time object, but not add two date-time objects." So, is the below expected behavior? > x <- Sys.time() > x [1] "2007-02-21 16:19:56 CST" > x + as.difftime("1","%H") [1] "2007-02-21 16:19:57 CST" Warning

Dear all, according to the Help-page of DateTimeClasses {base} I should be able to do time - z with time date-time objects z a numeric vector (in seconds) or an object of class "difftime". However, on R version 2.6.0 (Windows XP) I get > Sys.time() - as.difftime(c("0:3:20", "11:23:15")) Time differences in mins [1] 1191837998 1191837318

Hi, V1.8.0 seems to allow DateTimeClasses as the x argument in xyplots (lattice). For example: x <- seq.POSIXt(strptime("2003/01/01", format = "%Y/%m/%d"), strptime("2003/10/01", format = "%Y/%m/%d"), by = "month") y <- rnorm(length(x)) dat <- data.frame(x= x, y = y) xyplot(y ~ x, data = dat, type = "b")

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 think POSIXct and POSIXlt are badly-chosen names. The name "POSIX" implies UNIX. (i.e. XYZix operating system is mostly POSIX compliant... Woo-Hoo!). My assumption is that most people modelling industrial/econometric data etc, or data imported from databases, don't want system references everywhere. Historically, I've use the principle that: If programming language A uses

I am a beginner in R with a background in SAS. Are there built-in R methods of reading dates for calculating elapsed days between two calendar dates? If so, are there any examples I can browse? Thanks in anticipation. John Byrne. Lecturer in Information Systems. Australian Catholic University.

R V2.0.1 on Windows XP. I have read the help pages on strptime() over and over, but can't understand why strptime() is producing the following results. > v <- format("2002-11-31", format="%Y-%m-%d") > v [1] "2002-11-31" > factor(v, levels=v) [1] 2002-11-31 Levels: 2002-11-31 > x <- strptime("2002-11-31",