[R] time question
dwinsemius at comcast.net
Tue Nov 9 15:30:55 CET 2010
On Nov 9, 2010, at 9:18 AM, Ralf B wrote:
> I have this script which I use to get an epoch with accuracy of 1
> second (based on R's inability to calculate millisecond-accurate
> timestamps -- at least I have not seen a straightforward solution :)
From help page for Sys.time:
Sys.time returns an object of class "POSIXct" (see DateTimeClasses).
On almost all systems it will have sub-second accuracy: on systems
conforming to POSIX 1003.1-2001 the time will be reported in
microsecond increments. On Windows it increments in clock ticks (1/60
of a second) reported to millisecond accuracy."
You may be misled by the output of default formats.
> nowInSeconds <- as.numeric(Sys.time())
> nowInMS <- nowInSeconds * 1000
> when running this I get the following:
>> nowInSeconds <- as.numeric(Sys.time())
>> nowInMS <- nowInSeconds * 1000
>  1289312002
>  "1289312002093"
> I wonder where the 93 milliseconds come from. Is this a random number?
> A rounding error? Can somebody explain this?
David Winsemius, MD
West Hartford, CT
More information about the R-help