當前日期和時間

R 能夠訪問當前日期，時間和時區：

Sys.Date()             # Returns date as a Date object

## [1] "2016-07-21"

Sys.time()             # Returns date & time at current locale as a POSIXct object

## [1] "2016-07-21 10:04:39 CDT"

as.numeric(Sys.time()) # Seconds from UNIX Epoch (1970-01-01 00:00:00 UTC)

## [1] 1469113479

Sys.timezone()         # Time zone at current location

## [1] "Australia/Melbourne"

使用 OlsonNames() 查​​看當前系統上 Olson / IANA 資料庫中的時區名稱：

str(OlsonNames())
## chr [1:589] "Africa/Abidjan" "Africa/Accra" "Africa/Addis_Ababa" "Africa/Algiers" "Africa/Asmara" "Africa/Asmera" "Africa/Bamako" ...