grates (version 1.4.3)

period_class: Period class

Description

<grates_period> objects represent groupings of n consecutive days calculated relative to an offset. It is useful for when you wish to group an arbitrary number of dates together (e.g. 10 days).

Usage

as_period(x, n, ...)
# S3 method for default
as_period(x, n = 1L, offset = 0L, ...)
# S3 method for Date
as_period(x, n = 1L, offset = 0L, ...)
# S3 method for POSIXt
as_period(x, n = 1L, offset = 0L, ...)
# S3 method for character
as_period(x, n = 1L, offset = 0L, ...)
# S3 method for factor
as_period(x, n = 1L, offset = 0L, ...)
new_period(x = integer(), n = 1L, offset = 0L)
is_period(xx)

Value

A <grates_period> object.

Arguments

x, xx

R objects.

For as_period() this is the object to be coerced.

For new_period() this represents the number of periods since the Unix Epoch (1970-01-01) and a specified offset.

n

[integer]

Number of days that are being grouped.

...

Only used for character input where additional arguments are passed through to as.Date().

offset

[integer] or, for as_period(), a [date].

Value you wish to start counting periods from relative to the Unix Epoch:

• For integer values this is stored scaled by n (offset <- as.integer(offset) %% n).

• For date values this is first converted to an integer offset (offset <- floor(as.numeric(offset))) and then scaled via n as above.

Details

Internally grates_period objects are stored as the integer number, starting at 0, of periods since the Unix Epoch (1970-01-01) and a specified offset. Here periods are taken to mean groupings of n consecutive days. For storage and calculation purposes, offset is scaled relative to n (i.e. offset <- offset %% n) and values of x stored relative to this scaled offset.

as_period() is a generic for coercing input in to <grates_period> objects. It is the recommended way for constructing period objects as it allows the offset to be specified as a date (rather than an integer value relative to the Unix Epoch).

• Character input is first parsed using as.Date().

• POSIXct and POSIXlt are converted with their timezone respected.

new_period() is a minimal constructor for <grates_period> objects aimed at developers. It takes, as input, the number of periods since the Unix Epoch and the specified offset. double vectors will be converted via as.integer(floor(x)).

Examples

# coercion from date
dat <- as.Date("2012-12-01")
as_period(dat + 0:3, n = 2, offset = dat)

# direct construction
new_period(1:10)