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I have a vector of POSIXct values and I would like to round them to the nearest quarter hour. I don't care about the day. How do I convert the values to hours and minutes?
For example, I would like the value
"2012-05-30 20:41:21 UTC"
to be
"20:45"
824
So, use CEILING(A2,1/96) to round up to the next higher quarter hour. Use MROUND(A2,1/96) to round to the nearest quarter hour, and then use FLOOR(A2,1/96) to round to the lower quarter hour-- always goes back.
Add Up Time ManuallyDivide the minutes by 60. You'll usually get a whole number followed by one or two decimal points. If you're working with quarter hours, you may be able to refer to a standard chart instead. For example, 15 minutes equals one quarter-hour, or 0.25 hours.
For employers who track to the closest quarter hour, you should apply the “7-minute rule.” If an employee works an extra 1-7 minutes, the time can be rounded down to the closest quarter hour. If an employee works an extra 8-14 minutes, the time should be rounded up to the closest quarter hour.
Indeed, an old question with some helpful answers so far. The last one by giraffhere seems to be the most elegant. however, ist not floor_date but round_date which will do the trick:
lubridate::round_date(x, "15 minutes")
You can use round. The trick is to divide by 900 seconds (15 minutes * 60 seconds) before rounding and multiply by 900 afterwards:
a <-as.POSIXlt("2012-05-30 20:41:21 UTC")
b <-as.POSIXlt(round(as.double(a)/(15*60))*(15*60),origin=(as.POSIXlt('1970-01-01')))
b
[1] "2012-05-30 20:45:00 EDT"
To get only hour and minute, just use format
format(b,"%H:%M")
[1] "20:45"
as.character(format(b,"%H:%M"))
[1] "20:45"
something like
format(strptime("1970-01-01", "%Y-%m-%d", tz="UTC") + round(as.numeric(your.time)/900)*900,"%H:%M")
would work
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