R lubridate now 当前日期和时间

now(tzone = "")

today(tzone = "")

now()
#> [1] "2023-02-14 11:55:06 UTC"
now("GMT")
#> [1] "2023-02-14 11:55:06 GMT"
now("")
#> [1] "2023-02-14 11:55:06 UTC"
now() == now() # would be TRUE if computer processed both at the same instant
#> [1] FALSE
now() < now() # TRUE
#> [1] TRUE
now() > now() # FALSE
#> [1] FALSE
today()
#> [1] "2023-02-14"
today("GMT")
#> [1] "2023-02-14"
today() == today("GMT") # not always true
#> [1] TRUE
today() < as.Date("2999-01-01") # TRUE  (so far)
#> [1] TRUE