CODEWITHSUNDEEP
rposixctposixlt
user189035
user189035

Reputation: 5789

Rounding time to the next milisecond

Consider the date:

options(digits.secs = 6)
library(lubridate)

this_special_date <- with_tz(as.POSIXct(strptime('2017-11-20 23:00:00.051438000',
                                                 '%Y-%m-%d %H:%M:%OS', tz = 'GMT')),
                             tzone='Asia/Tokyo')

Now, I can use the function myformat.POSIXct from this answer to round it to the nearest milisecond:

myformat.POSIXct <- function(x, digits=0) {
  x2 <- round(unclass(x), digits)
  attributes(x2) <- attributes(x)
  x <- as.POSIXlt(x2)
  x$sec <- round(x$sec, digits) + 10^(-digits-1)
  format.POSIXlt(x, paste("%Y-%m-%d %H:%M:%OS",digits,sep=""))
}
myformat.POSIXct(this_special_date, digits=3)

return: "2017-11-21 08:00:00.051". But how to round a POSIXct time to the next miliseconds? --i.e. in the case above it would be "2017-11-21 08:00:00.052".

Upvotes: 0

Views: 111

Answers (2)

David Foster
David Foster

Reputation: 461

Could you add 00.0005 to all values? This would ensure that they are always rounded up relative to the starting value.

myformat.POSIXct <- function(x, digits=0) {
  x2 <- round(unclass(x + (5*10^(-digits-1))), digits)
  attributes(x2) <- attributes(x)
  x <- as.POSIXlt(x2)
  x$sec <- round(x$sec, digits) + 10^(-digits-1)
  format.POSIXlt(x, paste("%Y-%m-%d %H:%M:%OS",digits,sep=""))
}
myformat.POSIXct(this_special_date, digits=3)

Upvotes: 1

Roland
Roland

Reputation: 132969

myceil.POSIXct <- function(x, digits=0) {
  x1 <- as.numeric(x)
  x1 <- ceiling(x1 * 10 ^ digits) / 10 ^ digits
  attributes(x1) <- attributes(x)
  x1
}

myceil.POSIXct(this_special_date, 3)
#[1] "2017-11-21 08:00:00.052 JST"

Upvotes: 2

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