is.regular: Check Regularity of a Series

Description

is.regular is a regular function for checking whether a series of ordered observations has an underlying regularity or is even strictly regular.

Usage

is.regular(x, strict = FALSE)

Value

A logical is returned indicating whether x is (strictly) regular.

Arguments

x: an object (representing a series of ordered observations).
strict: logical. Should strict regularity be checked? See details.

Details

A time series can either be irregular (unequally spaced), strictly regular (equally spaced) or have an underlying regularity, i.e., be created from a regular series by omitting some observations. Here, the latter property is called regular. Consequently, regularity follows from strict regularity but not vice versa.

is.regular is a generic function for checking regularity (default) or strict regularity. Currently, it has methods for "ts" objects (which are always strictly regular), "zooreg" objects (which are at least regular), "zoo" objects (which can be either irregular, regular or even strictly regular) and a default method. The latter coerces x to "zoo" before checking its regularity.

Examples

Run this code

## checking of a strictly regular zoo series
z <- zoo(1:10, seq(2000, 2002.25, by = 0.25), frequency = 4)
z
class(z)
frequency(z) ## extraction of frequency attribute
is.regular(z)
is.regular(z, strict = TRUE)
## by omitting observations, the series is not strictly regular
is.regular(z[-3])
is.regular(z[-3], strict = TRUE)

## checking of a plain zoo series without frequency attribute
## which is in fact regular
z <- zoo(1:10, seq(2000, 2002.25, by = 0.25))
z
class(z)
frequency(z) ## data driven computation of frequency
is.regular(z)
is.regular(z, strict = TRUE)
## by omitting observations, the series is not strictly regular
is.regular(z[-3])
is.regular(z[-3], strict = TRUE)

suppressWarnings(RNGversion("3.5.0"))
set.seed(1)

## checking of an irregular zoo series
z <- zoo(1:10, rnorm(10))
z
class(z)
frequency(z) ## attempt of data-driven frequency computation
is.regular(z)
is.regular(z, strict = TRUE)