convert_expand: Expand messy dates to lists of dates

In messydates: A Flexible Class for Messy Dates

Expand messy dates to lists of dates

Description

These functions expand on date ranges, sets of dates, and unspecified or approximate dates (annotated with '..', '', 'XX' or '~'). As these messydates may refer to several possible dates, the function "opens" these values to reveal a vector of all the possible dates implied. Imprecise dates (dates only containing information on year and/or month) are also expanded to include possible dates within that year and/or month. The function removes the annotation from dates with unreliable sources ('?'), before being expanded normally as though they were incomplete.

Usage

expand(x, approx_range = 0, by = "day")

Arguments

x	A mdate object. If not an 'mdate' object, conversion is handled first with ´as_messydate()´.
approx_range	Range to expand approximate dates, or date components, annotated with '~', by default 0. That is, removes signs for approximate dates and treats these dates as precise dates. If 3, for example, adds 3 days for day approximation, 3 months for month approximation, 3 years for year/whole date approximation, 3 years and 3 months for year-month approximation, and 3 months and 3 days for month-day approximation.
by	Granularity of enumeration, "day" by default. To avoid combinatorial explosion, ranges are enumerated at day granularity and any time-of-day components on ranges are dropped. Precise date-times (i.e. non-ranges) keep their time. Set by to a sub-day unit ("hour", "min", or "sec") to opt in to finer enumeration of precise date-time ranges.

Value

A list of dates, including all dates in each range or set.

Examples

d <- as_messydate(c("2008-03-25", "-2012-02-27", "2001-01?", "~2001",
"2001-01-01..2001-02-02", "{2001-01-01,2001-02-02}", "{2001-01,2001-02-02}",
"2008-XX-31", "..2002-02-03", "2001-01-03..", "28 BC"))
expand(d)
# widen an approximate day (the '~' before the day) by 3 days either side
expand(as_messydate("2001-01-~15"), approx_range = 3)
# a precise date-time is returned unchanged, keeping its time
expand(as_messydate("2012-01-01 14:30:00"))
# a date-time range drops its time by default (day granularity)...
expand(as_messydate("2019-03-01 09:00..2019-03-01 12:00"))
# ...unless a sub-day 'by' is requested
expand(as_messydate("2019-03-01 09:00..2019-03-01 12:00"), by = "hour")

messydates documentation built on July 17, 2026, 1:07 a.m.