similar to: seq.default test for relative range (PR#1416)

I was surprised when seq.POSIXt() returned a single value rather than a vector, from inputs that I thought were reasonable. Here's an example to illustrate: > t0 <- ISOdatetime(2002,6,24,0,0,10) ## expected a sequence of 16 times 1 second apart > seq.POSIXt(from=t0,to=t0+15,by='1 sec') [1] "2002-06-24 00:00:10 PDT" ## traces to this call >

I have written a set of functions for POSIXt objects that I would like to offer for consideration for use in base R. They augment and extend existing functions. Briefly, ## pretty.ct function(x,specs=pretty.ct.specs) ## round.ct function(x, tstr='1 min' ) ## axis.ct function(side,x,specs=NULL,...) ## parse.timeint function(dv) ## parse.tstr

Conversion of a data frame to a matrix using as.matrix() when a column of the data frame is POSIXt and all other columns are numeric has changed in R 1.9.0 from R 1.8.1. The new behavior issues a warning message and converts to a character matrix. In R 1.8.1, such an object was converted to a numeric matrix. Here is an example. #### R 1.9.0 #### > foo <- data.frame(

There seems to be a problem in the way `+` is dispatched for POSIXt/difftime (R 2.8.0 Windows). With the following definitions: t0 <- as.POSIXct('2009-01-01 00:00') halfhour.mins <- as.difftime(30,units='mins') I would have thought that the straightforward answer to Suresh's question would be something like t0 + halfhour.mins * (0:47) And indeed, if we

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’m trying to export a file from R to excel using the xlsReadWritePro function and I keep getting the error below. I get the same error when I use the oledatetime function. My current date format is mm/dd/yyyy, which is how I want it in excel. Also is there anyway to export different datasets to multiple sheets similar to the ods function in SAS? <?xml:namespace prefix = o ns =

Hi ... I wonder if anyone can provide some insight into why the first three examples using the sunriset function (appended below, with results) give the correct answer, but the fourth generates and error. The first two use ISOdatetime with and without a time zone attribute, and the sunriset function returns the correct sunset time. The third and fourth adds 10 seconds to the ISOdatetime

Hello, I at first thought this was a system or locale issue, but since it occurs on both Windows and Linux and only for 2004 (AFAIK) I report it. I have a problem with as.POSIXct for the hour between "2004-10-03 02:00:00 GMT" and "2004-10-03 02:59:59 GMT". In short, the 2 AM (GMT) hour in 2004 (but not in other years) is interpreted as 1 AM by strptime: (I use ISOdatetime

For certain values, round.POSIXt(tm,'day') does not round to midnight as documented. The reason is that trunc.POSIXt() does not adjust the value of the isdst element. Assuming my assessment of the reason is correct, I have a potential solution to offer. Additional discussion is in bug report #1543. -Don > x <- c(as.POSIXct('2001-4-1 3:15'),as.POSIXct('2001-5-2

I think the following examples illustrate the crux of the matter (version and OS info are below). The problem has to do with the transition from standard time to daylight savings time. My timezone, US/Pacific, has two parts: standard time (PST) 8 hours behind GMT and daylight savings time (PDT) 7 hours behind GMT. The transition takes place this year on 7 April at 02:00, when 02:00 is

I've found several similar issues with write.table/read.table with Dates on this list, but trying to follow this advice I still get an error. First, I read in data from several files, constructing several date/time columns using ISOdatetime > str(Tall$Begin) 'POSIXct', format: chr [1:40114] "2005-10-02 00:00:00" "2005-10-02 00:00:00" ... > length(Tall$Begin)

I am finding that axis.POSIXct uses the local timezone for deciding where to put tic marks, even if the data being plotted are in another time zone. The solution is to use attr() to copy from the 'x' (provided as an argument) to the 'z' (used for the 'at' locations). I have pasted my proposed solution in section 1 below (as a diff). Then, in section 2, I'll put some

Hi all, I need to compare time series data files of different time formats. I had no problems with text format using strptime. But how can I convert datetime numbers from Excel (days since 30.12.1899 00:00:00) into POSIXt objects? For example 29770.375 should be converted to "03.07.1981 09:00:00" I tried the following code and encountered strange results: t1-t0 gives 29770.33

I'm having problems entering dates and times around when daylight savings time starts. If I type (on R 1.8.1 on Gentoo Linux) > ISOdatetime(2004,4,4,0:4,0,0,"GMT") [1] "2004-04-03 19:00:00 EST" "2004-04-03 20:00:00 EST" [3] "2004-04-03 22:00:00 EST" "2004-04-03 22:00:00 EST" [5] "2004-04-03 23:00:00 EST" Giving the times

I am trying to extract only the winters (defined to be 01-Dec through 28-Feb) of daily data from 1948-2002. There are 90 days in each winter season. I wrote the following code to gather the winter dates into a single vector: DJF <- NULL for(year in 1949:1999) { temp.begin <- strptime(paste("01/12", year-1, sep="/"), "%d/%m/%Y") temp.end <-

Dear list: working with date/times I have come across a problem that ISOdate and ISOdatetime are too slow on large vectors of data. I was surprised just until I looked at the implementation and the man page: "ISOdatetime and ISOdate are convenience wrappers for strptime". In other terms, they convert data to character representation first in order to create a POSIXlt object that is then

I can't reach r-project.org at the moment so cannot check whether this is a known bug. > version _ platform i386-pc-mingw32 arch x86 os Win32 system x86, Win32 status major 1 minor 3.0 year 2001 month 06 day 22 language R The

It appears that julian() is in R-base, but julian.default() is in the chron package. > search() [1] ".GlobalEnv" "package:ctest" "Autoloads" "package:base" > julian(1:3,4:6,1991:1993) Error in julian(1:3, 4:6, 1991:1993) : no applicable method for "julian" > find('julian') [1] "package:base" >

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

In addition to which, I would recommend df <- read.table("DATAM", header = TRUE, fill = TRUE, stringsAsFactors=FALSE) and then converting the Time column to POSIXct date-time values using as.POSIXct() specifying the format using formatting codes found in ?strptime because the times are not in the POSIXct default format. This example might indicate the idea: >