R: Utilities for creation and manipulation of 'Interval' objects

interval {lubridate} | R Documentation

## Utilities for creation and manipulation of `Interval` objects

### Description

`interval()` creates an Interval object with the specified start and end dates. If the start date occurs before the end date, the interval will be positive. Otherwise, it will be negative. Character vectors in ISO 8601 format are suported from v1.7.2.

`%--%` Creates an interval that covers the range spanned by two dates. It replaces the original behavior of lubridate, which created an interval by default whenever two date-times were subtracted.

`int_start()` and `int_start<-()` are accessors the start date of an interval. Note that changing the start date of an interval will change the length of the interval, since the end date will remain the same.

`int_end()` and `int_end<-()` are accessors the end date of an interval. Note that changing the end date of an interval will change the length of the interval, since the start date will remain the same.

`int_flip()` reverses the order of the start date and end date in an interval. The new interval takes place during the same timespan as the original interval, but has the opposite direction.

`int_shift()` shifts the start and end dates of an interval up or down the timeline by a specified amount. Note that this may change the exact length of the interval if the interval is shifted by a Period object. Intervals shifted by a Duration or difftime object will retain their exact length in seconds.

`int_overlaps()` tests if two intervals overlap.

`int_standardize()` ensures all intervals in an interval object are positive. If an interval is not positive, flip it so that it retains its endpoints but becomes positive.

`int_aligns()` tests if two intervals share an endpoint. The direction of each interval is ignored. int_align tests whether the earliest or latest moments of each interval occur at the same time.

`int_diff()` returns the intervals that occur between the elements of a vector of date-times. `int_diff()` is similar to the POSIXt and Date methods of `diff()`, but returns an Interval object instead of a difftime object.

### Usage

    interval(start, end = NULL, tzone = tz(start))

    start %--% end

    is.interval(x)

    int_start(int)

    int_start(int) <- value

    int_end(int)

    int_end(int) <- value

    int_length(int)

    int_flip(int)

    int_shift(int, by)

    int_overlaps(int1, int2)

    int_standardize(int)

    int_aligns(int1, int2)

    int_diff(times)

### Arguments

`start, end` | POSIXt, Date or a character vectors. When `start` is a character vector and end is `NULL`, ISO 8601 specification is assumed but with much more permisive lubridate style parsing both for dates and periods (see examples).
`tzone` | a recognized timezone to display the interval in
`x` | an R object
`int` | an interval object
`value` | interval's start/end to be assigned to `int`
`by` | A period or duration object to shift by (for `int_shift`)
`int1` | an Interval object (for `int_overlaps()`, `int_aligns()`)
`int2` | an Interval object (for `int_overlaps()`, `int_aligns()`)
`times` | A vector of POSIXct, POSIXlt or Date class date-times (for `int_diff()`)

### Details

Intervals are time spans bound by two real date-times. Intervals can be accurately converted to either period or duration objects using `as.period()`, `as.duration()`. Since an interval is anchored to a fixed history of time, both the exact number of seconds that passed and the number of variable length time units that occurred during the interval can be calculated.

### Value

`interval()` – Interval object.

`int_start()` and `int_end()` return a POSIXct date object when used as an accessor. Nothing when used as a setter.

`int_length()` – numeric length of the interval in seconds. A negative number connotes a negative interval.

`int_flip()` – flipped interval object

`int_shift()` – an Interval object

`int_overlaps()` – logical, TRUE if int1 and int2 overlap by at least one second. FALSE otherwise

`int_aligns()` – logical, TRUE if int1 and int2 begin or end on the same moment. FALSE otherwise

`int_diff()` – interval object that contains the n-1 intervals between the n date-time in times

### See Also

Interval, `as.interval()`, `%within%`

### Examples

    interval(ymd(20090201), ymd(20090101))

    date1 <- ymd_hms("2009-03-08 01:59:59")
    date2 <- ymd_hms("2000-02-29 12:00:00")
    interval(date2, date1)
    interval(date1, date2)
    span <- interval(ymd(20090101), ymd(20090201))

    ### ISO Intervals

    interval("2007-03-01T13:00:00Z/2008-05-11T15:30:00Z")
    interval("2007-03-01T13:00:00Z/P1Y2M10DT2H30M")
    interval("P1Y2M10DT2H30M/2008-05-11T15:30:00Z")
    interval("2008-05-11/P2H30M")

    ### More permisive parsing (as long as there are no intermittent / characters)
    interval("2008 05 11/P2hours 30minutes")
    interval("08 05 11/P 2h 30m")

    is.interval(period(months= 1, days = 15)) # FALSE
    is.interval(interval(ymd(20090801), ymd(20090809))) # TRUE
    int <- interval(ymd("2001-01-01"), ymd("2002-01-01"))
    int_start(int)
    int_start(int) <- ymd("2001-06-01")
    int

    int <- interval(ymd("2001-01-01"), ymd("2002-01-01"))
    int_end(int)
    int_end(int) <- ymd("2002-06-01")
    int
    int <- interval(ymd("2001-01-01"), ymd("2002-01-01"))
    int_length(int)
    int <- interval(ymd("2001-01-01"), ymd("2002-01-01"))
    int_flip(int)
    int <- interval(ymd("2001-01-01"), ymd("2002-01-01"))
    int_shift(int, duration(days = 11))
    int_shift(int, duration(hours = -1))
    int1 <- interval(ymd("2001-01-01"), ymd("2002-01-01"))
    int2 <- interval(ymd("2001-06-01"), ymd("2002-06-01"))
    int3 <- interval(ymd("2003-01-01"), ymd("2004-01-01"))

    int_overlaps(int1, int2) # TRUE
    int_overlaps(int1, int3) # FALSE
    int <- interval(ymd("2002-01-01"), ymd("2001-01-01"))
    int_standardize(int)
    int1 <- interval(ymd("2001-01-01"), ymd("2002-01-01"))
    int2 <- interval(ymd("2001-06-01"), ymd("2002-01-01"))
    int3 <- interval(ymd("2003-01-01"), ymd("2004-01-01"))

    int_aligns(int1, int2) # TRUE
    int_aligns(int1, int3) # FALSE
    dates <- now() + days(1:10)
    int_diff(dates)

[Package lubridate version 1.7.4 Index]