These functions are mainly convenience wrappers for the painful format()
and its strange codes...
Based on the requested time component, the output is as follows:
Year
returns the year of the input date in yyyy format or a yearmonth yyyymm.
Quarter
returns the quarter of the year (1 to 4) for the input date.
Month
returns the month of the year (1 to 12) for the input date or for a yearmonth yyyymm.
Week
returns the week of the year for the input date (0 to 53), as defined in ISO8601.
Weekday
returns the week day of the input date. (1 - Monday, 2 - Tuesday, ... 7 - Sunday). (Names and abbreviations are either english or in the current locale!)
YearDay
returns the day of the year numbering (1 to 366).
Day
returns the day of the month (1 to 31).
YearMonth
returns the yearmonth representation (yyyymm) of a date as long integer.
Hour
, Minute
, Second
, Timezone
return the hour, minute, second or timezone from a POSIXlt object.
HmsToMinute
converts the time parts of a POSIXlt object to minutes.
Today
, Now
return the current date, resp. the current date and time.
IsWeekend
returns TRUE
, if the date x falls on a weekend.
IsLeapYear
returns TRUE
, if the year of the date x is a leap year.
The day can not only be extracted, but as well be defined. See examples.
DiffDays360
calculates the difference between 2 dates using the 360-days convention.
LastDayOfMonth
returns the last day of the month of the given date(s).
YearDays
returns the total number of days of the given date(s).
MonthDays
returns the numer of days of the month of the given date(s).
The language in Weekday and Moth can be set with an option as well. The functions will check for an existing option named "lang" and take this value if it exists. So simply set option(lang="engl") if the results should always be reported in English.