Date-arithmetic {clock} | R Documentation |
These are Date methods for the arithmetic generics.
Calendrical based arithmetic:
These functions convert to a year-month-day calendar, perform the arithmetic, then convert back to a Date.
add_years()
add_quarters()
add_months()
Time point based arithmetic:
These functions convert to a time point, perform the arithmetic, then convert back to a Date.
add_weeks()
add_days()
## S3 method for class 'Date'
add_years(x, n, ..., invalid = NULL)
## S3 method for class 'Date'
add_quarters(x, n, ..., invalid = NULL)
## S3 method for class 'Date'
add_months(x, n, ..., invalid = NULL)
## S3 method for class 'Date'
add_weeks(x, n, ...)
## S3 method for class 'Date'
add_days(x, n, ...)
x |
A Date vector. |
n |
An integer vector to be converted to a duration, or a duration
corresponding to the arithmetic function being used. This corresponds
to the number of duration units to add. |
... |
These dots are for future extensions and must be empty. |
invalid |
One of the following invalid date resolution strategies:
Using either If If |
Adding a single quarter with add_quarters()
is equivalent to adding
3 months.
x
and n
are recycled against each other.
Only calendrical based arithmetic has the potential to generate invalid dates. Time point based arithmetic, like adding days, will always generate a valid date.
x
after performing the arithmetic.
x <- as.Date("2019-01-01")
add_years(x, 1:5)
y <- as.Date("2019-01-31")
# Adding 1 month to `y` generates an invalid date. Unlike year-month-day
# types, R's native Date type cannot handle invalid dates, so you must
# resolve them immediately. If you don't you get an error:
try(add_months(y, 1:2))
add_months(as_year_month_day(y), 1:2)
# Resolve invalid dates by specifying an invalid date resolution strategy
# with the `invalid` argument. Using `"previous"` here sets the date to
# the previous valid date - i.e. the end of the month.
add_months(y, 1:2, invalid = "previous")