subtract: Subtract numerics from mondates using day-of-month logic

In mondate: Keep Track of Dates in Terms of Months

Subtract numerics from mondates using day-of-month logic

Description

Subtract numerics from mondates. When units = "months" and the numeric is a whole number the result has the same day of the month subject to the number of days in the month, thus abandoning mondate's approach of representing days as fractional months. See examples.

Usage

subtract(e1, e2, units, forcelastday = FALSE)

Arguments

e1	a mondate
e2	anumeric
units	Anything allowed by base:::as.difftime. In addition, can be "months" or "years". If missing, defaults to timeunits(e1).
forcelastday	If FALSE, the result will have the same day of the month subject to the numbere of days in the month. If TRUE, the day of the month of the result will be the last day of the month if e1 is on the last day of the month.

Value

A mondate.

Author(s)

Dan Murphy.

Examples

x <- mondate(0:12)
subtract(x, 1)             # The third date will the the 29th of March
x <- mondate.ymd(2013, 2:12, 15)
subtract(x, 1)             # Always the 15th of the month. Compare to ...
x - 1
stopifnot(subtract(x, 1, units = "months") == mondate.ymd(2013, 1:11, 15))

mondate documentation built on May 29, 2024, 1:32 a.m.