similar to: POSIXct: Extract the hour for a list of elements

Hello, Following Dirk's post here: https://github.com/Rdatatable/data.table/issues/1619 we would like to clarify if this is the right behaviour, and if so, the rationale behind it. Here's the summary (thanks to Dirk and Joshua): Sys.setenv("TZ"="America/Chicago") dates = as.Date("2016-03-02") + (0:3)*7 # four Wednesdays # [1] "2016-03-02"

Hello, I found rather surprising the behaviour of POSIXct and POSIXlt classes when combined with min and tapply. The details can be deduced from the script below: ############# Start of the script #################### before <- Sys.time() Sys.sleep( 1 ) now1 <- now2 <- Sys.time() my.times <- c( before, now1, now2 ) class( my.times ) ## [1] "POSIXct"

POSIXct/lt supports fractional seconds (see Sub-second Accuracy section of man page), but there seem to be some inconsistencies in their handling. Converting to POSIXlt and back does not give back the same time for times before the origin: > t0 <- as.POSIXct('1934-01-05 23:59:59.00001') > t0 [1] "1934-01-06 00:00:00 EST" # rounding issue, see below >

In trying to use as.Date(), I've come across the conversion of POSIXlt to POSIXct when a POSIXlt variable is included in a data frame: my_POSIX <- strptime(c("11-09-2006", "11-10-2006", "11-11-2006", "11-12-2006", "11-13-2006"), "%m-%d-%Y") str(my_POSIX) my_Date <- as.Date(my_POSIX) str(my_Date) data <- format(my_Date)

R 2.6.1 on a Thinkpad T60 running up-to-date Gentoo: Despite the documentation, which says: 'strftime' is an alias for 'format.POSIXlt', and 'format.POSIXct' first converts to class '"POSIXlt"' by calling 'as.POSIXlt'. Note that only that conversion depends on the time zone. strftime fails on POSIXct objects: > foo <-

Full_Name: Erich Neuwirth Version: 2.3.1 OS: Windows XP, Linux Submission from: (NULL) (131.130.135.167) Converting Sys.Date() to a POSIX compliant time type in different ways produces inconsistent results: > Sys.date() [1] "2006-09-01" > as.POSIXct(Sys.Date()) [1] "2006-09-01 02:00:00 CEST" > as.POSIXlt(Sys.Date()) [1] "2006-09-01" >

In attempting to build R using rpmbuild --rebuild R-2.1.0-0.fdr.2.fc3.src.rpm on a fairly up-to-date RedHat 9 system (that is, with patches installed through May 1 2004), it failed at the make check-all step. The problem was reproducible by going into the tests directory and make test-Segfault The last lines of the saved file no-segfault.Rout.fail are > > ## c.POSIXct : > >

Although the documentation is somewhat sketchy, I() can be used to create objects of class AsIs: > I("a") [1] "a" attr(,"class") [1] "AsIs" "character" > I(4) [1] 4 attr(,"class") [1] "AsIs" "numeric" > I(4 + 0i) [1] 4+0i attr(,"class") [1] "AsIs" "complex" > This

Hi. This feels like a bug to me, or at least an undocumented feature, but I thought I'd see what people here thought of it. Consider a POSIXlt object like this one: > a <- as.POSIXlt ("2011-01-23 12:45:45") > class (a) [1] "POSIXlt" "POSIXt" Fine. Now, if I do some arithmetic on that object, the result is converted to POSIXct. > class (a

Hello folks, I found a strangeness while experimenting with POSIXct vectors and lists. It seems that coerced NA's aren't "real" NAs, at least as considered by is.na()? > date_vec = c(as.POSIXct(now()), as.POSIXct(now()+1),NA,"b") > date_vec [1] "2012-08-22 15:00:46 COT" "2012-08-22 15:00:47 COT" NA [4] NA Warning message: In

Dear R users, Given this data: x <- seq(1,100,1) dx <- as.POSIXct(x*900, origin="2007-06-01 00:00:00") dfx <- data.frame(dx) Now to play around for example: subset(dfx, dx > as.POSIXct("2007-06-01 16:00:00")) Ok. Now for some reason I want to extract the datapoints between hours 10:00:00 and 14:00:00, so I thought well: subset(dfx, dx >

Hey R folks, i found some strange (to me) behaviour with chron to POSIXct conversion. The two lines of code result in two different results, on ewith the correct time zone, one without: library(chron) as.POSIXct(chron('12/12/2000'), tz = 'UTC') as.POSIXlt(chron('12/12/2000'), tz = 'UTC') Only the code below would give me a POSIXct object with the correct time

Thank you, Jskud. I can reproduce your problem, though not the seg.fault, see below >>>>> "Jskud" == Jskud <Jskud@Jskud.com> >>>>> on Sat, 30 Apr 2005 09:04:03 +0200 (CEST) writes: Jskud> In attempting to build R using rpmbuild --rebuild Jskud> R-2.1.0-0.fdr.2.fc3.src.rpm Jskud> on a fairly up-to-date RedHat 9 system (that

1) Why did you submit this *twice*, as PR#7826 and PR#7827? Please don't be so careless of the volunteers' time. 2) > print.POSIXct function (x, ...) { print(format(x, usetz = TRUE, ...), ...) invisible(x) } is definitely *not* implicated. (Use of ... in two places is correct.) 3) On FC3: > unusual_and_faults Error: protect(): protection stack overflow >

Bumping this up to the front again ... because it exhibits a difference in behaviour of R across OSs. Such a 'feature' may not be desirable. On 4 April 2016 at 18:00, Arunkumar Srinivasan wrote: | Hello, | | Following Dirk's post here: https://github.com/Rdatatable/data.table/issues/1619 | we would like to clarify if this is the right behaviour, and if so, | the rationale behind it.

Hello, I searched the archives but could not come to a solution. I have to two columns of information t_start_cdt looks like: > t_start_cdt[1:4] [1] "2003-07-09 11:02:25" "2003-07-09 11:10:25" "2003-07-09 11:30:25" [4] "2003-07-09 12:00:25" > class(t_start_cdt) [1] "POSIXt" "POSIXlt" t_end_cdt looks like: > t_end_cdt[1:4]

Dear R-helpers, I have a problem converting an object made with the 'chron' function to a POSIXct object: # Make date based on DOY dat <- chron(dates=232, origin.=c(month=1, day=1, year=2008)) dat #[1] 08/20/08 # Converting to POSIXct uses current timezone (Sydney): as.POSIXct(dat) #[1] "2008-08-20 10:00:00 EST" # Setting GMT timezone has no effect? as.POSIXct(dat,

Hello R users I am searching for a descriptive summary of the use of POSIXlt as compared to POSIXct date/time formats. I have been using them extensively for different purposes, but still can't quite understand when to use which one for the most efficient coding and use. I typically use them in graphics, comparison of times, interpolation of values between times, computation of

Hi, I 'd like to know how to extract an interval of "hour:minute" type from a column of POSIXlt POSIXct type. For instance: my_data.csv: 4352;2011-09-02 21:30:00;3242; 4352;2011-09-02 21:31:00;3315; 4352;2011-09-02 21:32:00;4241; 4352;2011-09-02 21:33:00;5394; ... 4352;2011-09-02 01:02:00;67; 4352;2011-09-02 01:03:00;67; 4352;2011-09-02 01:04:00;67; .... I loaded

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