YYYYMMDDHH
A character vector (or its factor equivalent) of dates in the form
YYYYMMDDHH or YYYYMMDD, in which YYYY specifies the year, MM the
month, DD the day, and (optionally) HH the hour.
origin
A named vector specifying the month, day, and year for the
origin of the Julian dates. The default is
c(month = 1, day = 1, year = 2000)
.