class: A flexible date class for messy dates

In messydates: A Flexible Class for Messy Dates

A flexible date class for messy dates

Description

Recent extensions to standardised date notation in ISO 8601-2_2019(E) create space for unspecified, uncertain, and approximate dates, as well as succinct representation of ranges of dates. These functions create and validate a new date class for R that can contain and parse these annotations, and are not typically user-facing. Please see as_messydate() for the user-facing coercion function.

Usage

new_messydate(x = character())

validate_messydate(x)

Arguments

x	A character scalar or vector in the expected "yyyy-mm-dd" format annotated, as necessary, according to ISO 8601-2_2019(E).

Details

Date annotations

Unspecified date components, such as when the day is unknown, can be represented by one or more Xs in place of the digits. The modifier * is recommended to indicate that the entire time scale component value is unspecified, e.g. X*-03-03, however this is not implemented here. Please be explicit about the digits that are unspecified, e.g. XXXX-03-03 expresses 3rd March in some unspecified year, whereas 2003-XX-03 expresses the 3rd of some month in 2003. If time components are not given, they are expanded to this.

Approximate date components, modified by ~, represent an estimate whose value is asserted to be possibly correct. For example, 2003~-03-03 The degree of confidence in approximation depends on the application.

Uncertain date components, modified by ⁠?⁠, represent a date component whose source is considered to be dubious and therefore not to be relied upon. An additional modifier, ⁠%⁠, is used to indicate a value that is both uncertain and approximate.

Date sets

These functions also introduce standard notation for ranges of dates. Rather than the typical R notation for ranges, :, ISO 8601-2_2019(E) recommends ... This then can be applied between two time scale components to create a standard range between these dates (inclusive), e.g. ⁠2009-01-01..2019-01-01⁠. But it can also be used as an affix, indicating "on or before" if used as a prefix, e.g. ..2019-01-01, or indicating "on or after" if used as a suffix, e.g. ⁠2009-01-01..⁠.

And lastly, notation for sets of dates is also included. Here braces, {}, are used to mean "all members of the set", while brackets, ⁠[]⁠, are used to mean "one member of the set".

Value

Object of class mdate

See Also

messydate

messydates documentation built on May 29, 2024, 2:16 a.m.