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, ...)

## S3 method for class 'integer':
as.Date(x, ...)
## S3 method for class 'ts':
as.Date(x, offset = 0, ...)

Arguments

Details

The as.Date.integer method interprets the argument x as the number of days since the origin 1970-01-01 so that the origin corresponds to 0. Negative values are allowed.

The as.Date.numeric method like the as.Date.integer method applied to floor(x).

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.

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.

See Also

Date for details of the date class

Examples

as.Date(0) # origin, i.e. 1970-01-01

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

# both result in ten firsts of year starting 2001-01-01
as.Date(ts(rnorm(10)), offset = 2000)
as.Date(ts(rnorm(10), start = 2001))  

# both result in ten firsts of month starting with 1990-01-01
as.Date(ts(rnorm(10), start = c(90,1), freq = 12), offset = 1900)  
as.Date(ts(rnorm(10), start = c(1990,1), freq = 12))