| is.date {date} | R Documentation |
Tests for objects of class "date".
is.date(x) as.date(x)
x |
any R object. |
is.date returns TRUE if x has mode
"date", and FALSE otherwise.
Its behavor is unaffected by any attributes of x; for
example, x could be a date array (in contrast to the behavior
of is.vector).
as.date returns x if x is a simple object of
class "date", and otherwise a date vector of the same length
as x and with data resulting from coercing the elements of
x to class "date". See the manual page for
as.date() for details.
Dates are stored as the number of days since 1/1/1960, and are kept
in integer format. (This is the same baseline value as is used by
SAS). The numerical methods for dates treat date - date as a
numeric, and date +- numeric as a date.
Logical operations as well as the numeric functions exp(),
log(), and so on are invalid.
Other methods exist for missing value, as.character(),
printing, and summarizing.
date.mdy,
mdy.date,
date.ddmmmyy,
as.date.