as.Date.numeric: Date Conversion Functions from Numeric, Integer and ts Objects

Description

Functions to convert numeric and related classes to objects of class "Date" representing calendar dates.

Usage

## S3 method for class 'numeric':
as.Date(x, origin = "1970-01-01", \dots)
## S3 method for class 'ts':
as.Date(x, offset = 0, \dots)

Arguments

numeric or an object of class "ts", respectively.

origin

A specification of the origin for the dates (x days since origin).

offset

A value added to time(x).

...

Further arguments. Currently not used.

Value

The as.Date methods return an object of class "Date". In the case of as.Date.ts applied to a yearly, quarterly or monthly series the earliest date, i.e., first of year, quarter or month, is returned.

Details

The as.Date method for numeric arguments x interprets x the number of days since the origin (default: 1970-01-01). Negative values are allowed.

The as.Date.ts inspects time(x) and frequency(x): If the frequency is 1 or 4 or 12, time(x) is regarded to be annual, quarterly or monthly data respectively. If the frequency is something else, no coercion is done.

Examples

Run this code

# uses origin = "1970-01-01"
as.Date(0) 

# all three result in origin and next 9 days
as.Date(0:9)
as.Date(0) + 0:9
x <- ts(rnorm(10), start = 0)
as.Date(unclass(time(x)))

# annual/quarterly/monthly series:
xa <- ts(rnorm(10), start = 2001)
xq <- ts(rnorm(10), start = 2001, freq = 4)
xm <- ts(rnorm(10), start = 2001, freq = 12)
as.Date(time(xa))
as.Date(time(xq))
as.Date(time(xm))

# using offset argument
xa2 <- ts(rnorm(10))
as.Date(time(xa2), offset = 2000)