Strip the date and keep the time

Question

Lots of people ask how to strip the time and keep the date, but what about the other way around? Given:

myDateTime <- \"11/02/2014 14:22:45\"


        

Answer 1

If the time within a GMT day is useful for your problem, you can get this with %%, the remainder operator, taking the remainder modulo 86400 (the number of seconds in a day).

stamps <- c("2013-04-12 19:00:00", "2010-04-01 19:00:01", "2018-06-18 19:00:02")
as.numeric(as.POSIXct(stamps)) %% 86400
## [1] 0 1 2

Answer 2

I think you're looking for the format function.

(x <- strptime(myDateTime, format="%d/%m/%Y %H:%M:%S"))
#[1] "2014-02-11 14:22:45"
format(x, "%H:%M:%S")
#[1] "14:22:45"

That's character, not "time", but would work with something like aggregate if that's what you mean by "analyse events recorded over several days by time of day only."