Find the finest or coarsest common chronon of a time object

These utility functions take a set of chronons and identify a common chronon that can represent all input chronons without loss of information, using the ordered relationships defined by chronon_cardinality() methods. This is useful for operations that require a shared time granule, such as combining or comparing different time measured at different precisions.

chronon_glb() finds the greatest lower bound (GLB): the common chronon of the finest granularity that can represent all input chronons without loss of information.

chronon_lub() finds the least upper bound (LUB): the common chronon of the coarsest granularity that every input chronon evenly aggregates into - the dual of chronon_glb().

chronon_common() was renamed to chronon_glb() to distinguish it from its dual, chronon_lub().

Usage

chronon_glb(x, ...)

chronon_glb.mixtime(x, .ptype = NULL, ...)

chronon_lub(x, ...)

chronon_lub.mixtime(x, .ptype = NULL, ...)

chronon_common(x, .ptype = NULL, ...)

Arguments

x

A time object (typically a mixtime).

...

Additional arguments for methods.

.ptype

If NULL, the default, the output returns the common chronon across all chronons of x. Alternatively, a prototype chronon can be supplied to .ptype to demand a specific chronon is used. If the supplied .ptype cannot represent all input chronons without loss of information, an error is raised.

Value

A time granule object representing the common chronon.

Examples

# The finest common chronon between a year-month and a day is a day
chronon_glb(c(yearmonth(Sys.Date()), date(Sys.Date())))
#> <mixtime::tu_day>
#>  @ n : int 1
#>  @ tz: chr NA

# The finest common chronon between a Gregorian month and an ISO week is a day
chronon_glb(c(yearweek(Sys.Date()), yearmonth(Sys.Date())))
#> <mixtime::tu_day>
#>  @ n : int 1
#>  @ tz: chr NA

# The finest common chronon between a ISO week and an hour is an hour
chronon_glb(c(yearweek(Sys.Date()), linear_time(Sys.time(), hour(1L))))
#> <mixtime::tu_hour>
#>  @ n : int 1
#>  @ tz: chr NA

# The coarsest common chronon between a second and a minute is a minute
chronon_lub(c(linear_time(Sys.time(), second(1L)), linear_time(Sys.time(), minute(1L))))
#> <mixtime::tu_minute>
#>  @ n : int 1
#>  @ tz: chr "UTC"