similar to: Problem with POSIXct in ave

Dear All, what determines if a difference between POSIXct objects gets expressed in days or seconds? In the following example, it's sometimes seconds, sometimes days. as.POSIXct('2009-09-01') - as.POSIXct(NA) Time difference of NA secs c(as.POSIXct('2009-09-01'), as.POSIXct(NA)) - c(as.POSIXct('2009-09-01'), as.POSIXct('2009-08-31')) Time differences in

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]

Hello, I wanted to compute the time differenze between to times: first =as.POSIXct( "2012-06-15 16:32:39.0025 CEST") second = as.POSIXct("2012-06-15 16:32:39.0086 CEST") second - first The result is Time difference of 0.006099939 secs instead of just 0.0061 secs So R adds aditional numbers after the result. I know I could round it in this case. But I am working with a

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

R developers, The "tzone" attribute is stripped from a POSIXct object when the subscript command is called ("[.POISXct"). This results in dates being printed in the locale specific format after a subscript operation is applied to a POSIXct object which has cause several problems for me in the past. Here is an example of this problem under R 1.9.1: > x <-

Hi, I have a data frame with two columns: dt and tf. The dt column is datetime and the tf column is a temperature. dt tf 1 2009-06-20 00:53:00 73 2 2009-06-20 01:08:00 73 3 2009-06-20 01:44:00 72 4 2009-06-20 01:53:00 71 5 2009-06-20 02:07:00 72 ... I need a subset of the rows where the minutes are 53. The hour is immaterial. I can not find a wildcard

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

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"))

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, I'm having problems working with date values in POSIXct format. Here is what I got (eg.lig attached): x <- read.table("eg.txt", sep = ',', col.names=c("ok","time","secs","lig")) # it gives time as factor z <- cbind(x,colsplit(x$time, split="\\s", names=c("date", "clock")))

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 >

Hello all!!! I want to measure the duration of events (given a start and an end time). The catch is that I require the output in calender days. This means: 02-Jan-2011 00:01:00 minus 01-Jan-2011 23:59:00 should be 1 day (although the real time difference is only 2 minutes) My data is the following head(episode.ct) [1] "2009-07-13 13:37:20 CEST" "2009-07-14 07:29:20 CEST"

Hola a todos: Tengo un problema con las fechas, básicamente necesito una diferencia en días y siempre se sale en segundos. Salvo un ejemplo copiado de un libro, pero yo necesito procesar los datos propios. Les paso el código en R (copiar y pegar, son solo dos días que se comparan) y al final como me salen los resultados porque es medio complicada mi redacción. ¿Alguna idea? fechas1

I just encountered another RTFM problem: With diff(as.POSIXct(...), ...) I was unable to control the units of the results. Examples: > (d.d <- diff(as.POSIXct(c('2012-12-12', '2012-12-13')))) Time difference of 1 days > (d.h <- diff(as.POSIXct(c('2012-12-12 08:00', '2012-12-12 09:00')))) Time difference of 1 hours > (d.m <-

Hi I just started using RGui.exe under widnows. I have a text file containing date arranged in columns and rows, each column has the same format, each row with different formats. 3 of the columns are something like this 1/12/2006 3:59:45 PM I need to calculate the different in seconds between 2 selected periods using their row’s index My solution: Read the file in a data frame and

Hi. I'm trying to take the difference in days between two times. Can you point out what's wrong, or suggest a different function? When I try the following code, The following code works fine: a <- strptime(1911100807,format="%Y%m%d%H",tz="GMT") b <- strptime(1911102718,format="%Y%m%d%H",tz="GMT") x <- difftime(b, a,

I have two dataframe columns of POXIXct data/times that include seconds. I got them into this format using for example zsort$ETA <- as.POSIXct(as.character(zsort$ETA), format="%m/%d/%Y %H:%M:%S") My problem is that when I subtract the two columns, sometimes the difference is given in seconds, and sometimes it is given in minutes. I don't care which it is, but I need to know which

Hi, I would like to merge two data frames. It is just that I want the merging to be done with some kind of a fuzzy criterion. Let me explain. My first data frame looks like this : ID1 time1 dt 1 2008-01-02 13:11 10 2 2008-01-02 14:20 20 3

Dear R-Users, I have a data file with timestamps and I wanted to use POSIXct time data type to represent the respective column. I played around with the type and found a couple of issues: * there seems to be no direct way of reading datetimes into a variable. Let's say this is my file "1992-02-27 23:03:20 PST" "1992-02-27 22:29:56 PST" "1992-01-14 01:03:30 PST"

I have just become painfully aware that objects of class "difftime", generated by the difference of two POSIXct objects, carry a "units" attribute, which flashes by when the object is printed, for example. The pain was occasioned when I tried to turn these objects into numberic objects for use elsewhere as a covariate. as.numeric(difftime object) simply turns off the units