At any rate, one idea is to create the chron dates relative to the default origin like this:
> testDATES<-c(35947,35971,36004,36008,36053,36066)testDATES.chron <- chron("12/30/1899") + testDATES> as.POSIXct(testDATES.chron) [1] "1998-05-31 20:00:00 Eastern Daylight Time" [2] "1998-06-24 20:00:00 Eastern Daylight Time" [3] "1998-07-27 20:00:00 Eastern Daylight Time" [4] "1998-07-31 20:00:00 Eastern Daylight Time" [5] "1998-09-14 20:00:00 Eastern Daylight Time" [6] "1998-09-27 20:00:00 Eastern Daylight Time"
Does that make any difference on your system?
This worked on my machine as well! I'm not sure why this made a difference...but thanks.
Brian
--- Date: Fri, 5 Mar 2004 11:35:45 -0500 From: Brian Beckage <[EMAIL PROTECTED]> To: <[EMAIL PROTECTED]> Subject: [R] as.POSIXct problem
Hi all,
I'm having difficulty converting a 'dates' object to a POSIXct object:
testDATES<-c(35947,35971,36004,36008,36053,36066)
testDATES<-chron(dates=testDATES, format = c(dates = "m/d/y"), origin=c(month = 12, day = 30, year = 1899))
[1] 06/01/98 06/25/98 07/28/98 08/01/98 09/15/98 09/28/98
as.POSIXct(testDATES)[1] NA NA NA NA NA NA
format(as.POSIXct(testDATES), "%m/%d/%Y")[1] NA NA NA NA NA NA
I've looked at the as.POSIXct function, traced the problem to ISOdate and then to strptime, e.g.,
x<-paste(year=1899, month=12, day=30, hour=12, min=0, sec=0)x "1899 12 30 12 0 0"
strptime(x, "%Y %m %d %H %M %S") [1] NA NA NA NA
However, strptime works fine below.
dates <- c("02/27/92", "02/27/92", "01/14/92", "02/28/92", "02/01/92") strptime(dates, "%m/%d/%y")"02/27/92" "02/27/92" "01/14/92" "02/28/92" "02/01/92"
I've been reading through a whole suite of emails on the R archives regarding as.POSIXct problems but I have not found anything that solves my particular problem. I need the dates to be of class POSIXct for use in the its package.
I'm using R 1.8.1 on Mac OS 10.3.2. Any help is greatly appreciated.
Thanks, Brian
-- ********************************************************************* Brian Beckage Department of Botany University of Vermont Marsh Life Science Building Burlington, VT 05405
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-- ********************************************************************* Brian Beckage Department of Botany University of Vermont Marsh Life Science Building Burlington, VT 05405
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