Round an POSIXct date up to the next day

Question

I have a question similar to Round a POSIX date (POSIXct) with base R functionality, but I'm hoping to always round the date up to midnight the next day (00:00:00).

Basically, I want a function equivalent to ceiling for POSIX-formatted dates. As with the related question, I'm writing my own package, and I already have several package dependencies so I don't want to add more. Is there a simple way to do this in base R?

You're going to have issues with timezones and daylight saving time. Just use `Date` if you don't need the time component. — Joshua Ulrich, Aug 09 '12 at 17:52
I'm web scraping POSIXct-style timestamps, and I'm trying to round them to the next day. I don't know if the `Date` format would work for that... — Eli Sander, Aug 09 '12 at 18:08
So you have POSIXct-style character strings... can't you just strip the time component from the string, convert to `Date` and add 1 to the result? — Joshua Ulrich, Aug 09 '12 at 18:11
I'm actually getting UNIX-style timestamps, which are in nanoseconds. So I was going to strip the nanoseconds and convert to POSIXct, then work with them from there. — Eli Sander, Aug 09 '12 at 18:12
It would be useful if you could provide an example of your input (including timezone, if applicable), how you're converting it to POSIXct, and the desired output (including timezone, if applicable). — Joshua Ulrich, Aug 09 '12 at 18:33

score 9 · Accepted Answer · answered Aug 09 '12 at 17:55

9

Maybe

trunc(x,"days") + 60*60*24

> x <- as.POSIXct(Sys.time())
> x
[1] "2012-08-09 18:40:08 BST"
> trunc(x,"days")+ 60*60*24
[1] "2012-08-10 BST"

answered Aug 09 '12 at 17:55

shhhhimhuntingrabbits

7,397
2
23
23

score 0 · Answer 2 · answered Aug 09 '12 at 18:00

A quick and dirty method is to convert to a Date (which truncates the time), add 1 (which is a day for Date) and then convert back to POSIX to be at midnight UTC on the next day. As @Joshua Ulrich points out, timezone/daylight savings issues may give results you don't expect:

as.POSIXct(as.Date(Sys.time())+1)
[1] "2012-08-10 01:00:00 BST"

Round an POSIXct date up to the next day

2 Answers2