An era object defines the time scale associated with a vector of years
(see yr()). era() returns an era object, either by looking up
label in the standard eras defined in eras() or, if more than one
argument is given, constructing a new definition with the specified
parameters.
Usage
era(
label = character(),
epoch = NULL,
name = label,
unit = era_year("Gregorian"),
scale = 1,
direction = -1
)
Value
An object of class era.
Arguments
label
Character. If only one argument is given to era(), the
abbreviated label of a standard era defined in eras().
Otherwise, the label to give to the era constructed using the following
arguments.
epoch
Numeric. Epoch year from which years are counted in Gregorian
astronomical years (i.e. there is a "year zero").
name
Character. Full name of the era. Defaults to the value of
label.
unit
An era_year() object describing the name of the year unit and
its average length in solar days. Defaults to a Gregorian year
(365.2425 days).
scale
Integer. Number of years represented by one unit, e.g. 1000
for ka. Default: 1.
direction
Are years counted backwards (-1) (the default) or forwards (1)
from epoch?
See Also
Other era definition functions:
eras()
Other era helper functions:
era_parameters,
era_year_parameters,
era_year,
is_era_year(),
is_era(),
is_yr(),
this_year()