Get/set weeks component of a date-time

week() returns the number of complete seven day periods that have occurred between the date and January 1st, plus one.

isoweek() returns the week as it would appear in the ISO 8601 system, which uses a reoccurring leap week.

epiweek() is the US CDC version of epidemiological week. It follows same rules as isoweek() but starts on Sunday. In other parts of the world the convention is to start epidemiological weeks on Monday, which is the same as isoweek.

Usage

week(x)

week(x) <- value

isoweek(x)

epiweek(x)

Arguments

x

a date-time object. Must be a POSIXct, POSIXlt, Date, chron, yearmon, yearqtr, zoo, zooreg, timeDate, xts, its, ti, jul, timeSeries, or fts object.

value

a numeric object

Value

the weeks element of x as an integer number

References

https://en.wikipedia.org/wiki/ISO_week_date

See also

isoyear()

Examples

x <- ymd("2012-03-26")
week(x)
#> [1] 13
week(x) <- 1
week(x) <- 54
week(x) > 3
#> [1] FALSE