lubridate (version 1.7.0)

fit_to_timeline: Fit a POSIXlt date-time to the timeline

Description

The POSIXlt format allows you to create instants that do not exist in real life due to daylight savings time and other conventions. fit_to_timeline matches POSIXlt date-times to a real times. If an instant does not exist, fit to timeline will replace it with an NA. If an instant does exist, but has been paired with an incorrect timezone/daylight savings time combination, fit_to_timeline returns the instant with the correct combination.

Usage

fit_to_timeline(lt, class = "POSIXct", simple = FALSE)

Arguments

lt

a POSIXlt date-time object.

class

a character string that describes what type of object to return, POSIXlt or POSIXct. Defaults to POSIXct. This is an optimization to avoid needless conversions.

simple

if TRUE, lubridate makes no attempt to detect meaningless time-dates or to correct time zones. No NAs are produced and the most meaningful valid dates are returned instead. See examples.

Value

a POSIXct or POSIXlt object that contains no illusory date-times

Examples

# NOT RUN {
tricky <- structure(list(sec   = c(5,    0,    0,    -1),
                         min   = c(0L,   5L,   5L,   0L),
                         hour  = c(2L,   0L,   2L,   2L),
                         mday  = c(4L,   4L,   14L,  4L),
                         mon   = c(10L,  10L,  2L,   10L),
                         year  = c(112L, 112L, 110L, 112L),
                         wday  = c(0L,   0L,   0L,   0L),
                         yday  = c(308L, 308L, 72L,  308L),
                         isdst = c(1L,   0L,   0L,   1L)),
                    .Names = c("sec", "min", "hour", "mday", "mon",
                               "year", "wday", "yday",  "isdst"),
                    class = c("POSIXlt", "POSIXt"),
                    tzone = c("America/Chicago", "CST", "CDT"))

tricky
## [1] "2012-11-04 02:00:00 CDT" Doesn't exist because clocks "fall back" to 1:00 CST
## [2] "2012-11-04 00:05:00 CST" Times are still CDT, not CST at this instant
## [3] "2010-03-14 02:00:00 CDT" DST gap
## [4] "2012-11-04 01:59:59 CDT" Does exist, but has deceptive internal structure

fit_to_timeline(tricky)
## Returns:
## [1] "2012-11-04 02:00:00 CST" instant paired with correct tz & DST combination
## [2] "2012-11-04 00:05:00 CDT" instant paired with correct tz & DST combination
## [3] NA - fake time changed to NA (compare to as.POSIXct(tricky))
## [4] "2012-11-04 01:59:59 CDT" -real instant, left as is

fit_to_timeline(tricky, simple = TRUE)
## Returns valid time-dates by extrapolating CDT and CST zones:
## [1] "2012-11-04 01:00:05 CST" "2012-11-04 01:05:00 CDT"
## [3] "2010-03-14 03:05:00 CDT" "2012-11-04 01:59:59 CDT"
# }