similar to: Unexpected behavior of difftime in relationship to daylight savings time

Colleagues, I submitted this several days ago and no one responded, so I am trying again, trying a different subject line: 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 results below suggests that R (version 2.8.0 in OS X) implements the

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"))

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]

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'

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

R 2.15.1 OS X Colleagues, I encountered the following unexpected behavior today: The following command yielded the expected result: paste(c("TEXT1", "TEXT2"), collapse="|") Result: [1] "TEXT1|TEXT2" However, abbreviating "collapse" by even one character: paste(c("TEXT1", "TEXT2"), collaps="|") yielded the

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

Colleagues, I want to create the following array: "A1", "A2", "A3", "B1", "B2", "B3", "C1", "C2", "C3" I recall that there is a trick using "c" or "paste" permitting me to form all combinations of c("A", "B", "C") and 1:3. But, I can't recall the

Colleagues, Hopefully a simple problem: I want to delete a column with a known name from a dataframe. I could write: FRAME <- FRAME[, names(FRAME) != NAMETODELETE] or FRAME <- FRAME[, !names(FRAME) %in% c(NAME1, NAME2, ETC)] Is there some simpler means to accomplish this? Dennis Dennis Fisher MD P < (The "P Less Than" Company) Phone: 1-866-PLessThan (1-866-753-7784)

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

Colleagues, I am interesting in opening a PDF document via the command line from both Windows, OS X, and Linux ( R version 2.8.0). I found a command openPDF in Biobase. However, I would rather execute the command myself. For example, in OS X: > system("open filename.pdf") is successful. Is there a comparable command line command for Windows or Linux? Dennis Dennis Fisher

I run R 2.1.1 in a Linux environment (RedHat 9) although my question is not platform-specific. Consider the following: > A <- c("Prefix-aaa", "Prefix-bbb", "Prefix-ccc") > B <- strsplit(A, "-") > B [[1]] [1] "Prefix" "aaa" [[2]] [1] "Prefix" "bbb" [[3]] [1] "Prefix" "ccc" How

Colleagues After reading in some clinical data, I discovered that the subject ID column contains entries only for the first record for each individual; subsequent rows are recorded as NA. For example: > 1 > NA > NA > NA > NA > 2 > NA > NA > NA > NA > 3 > NA > NA > ... I can think of various approaches to replace the NA values with appropriate

Colleagues, I have some text: TEXT <- c("a", "bb;ccc", "dddd;eeeee;ffffff") I want to retrieve the portion of each element before the first semicolon. I can split each element using strsplit: SPLIT <- strsplit(TEXT, ";") This yields: > SPLIT [[1]] [1] "a" [[2]] [1] "bb" "ccc" [[3]] [1] "dddd"

I have data in the following format: > DATE [1] "01/13/2004" In order to find the difference between two data points, I presently use brute force to calculate the day of the year: > strptime(DATE, format="%m/%d/%Y")$yday [1] 12 Although this works, it may not be robust over different years. I assume that R is sufficiently clever that a much simpler approach

Colleagues, (Running R 2.7.0) I have a script that I want to delete as it completes execution. The penultimate line of the script (before the quit command) is: file.remove("Scriptname") The script is executed as: R --no-save < Scriptname In OS X and Linux this is successful and returns: > > file.remove("x") > [1] TRUE and the file is deleted In Windows XP,

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

Colleagues, I have encountered behavior of random number generation that eludes me. I generate a random integer in a particular range using the following code: sample(1000:9999, size=1) This code exists within a script that starts with the command: remove(list=ls()) Each time that I run the script, it yields the same random number: 6420. I thought that the problem might result from

Colleagues, I have encountered a problem in version 2.9 of R, running in both Vista and OS X. My code is quite lengthy but the critical line is: if (file.exists(FILENAME)) readLines(FILENAME)) This triggers the error: Error in file(con, "r") : cannot open the connection Calls: readLines -> file Execution halted The file that it is reading is being created on the fly, then

Colleagues I frequently insert PDF graphics created with R into Word (Office 2004 for Mac) documents. The documents are created on either a Linux machine (RedHat 9) or a Mac (Tiger). I am using R 2.2.0. These pdf graphics often lose a great deal of resolution after insertion into Word compared to their high quality when printed as PDF documents. I recently learned that converting the