lubridate (tidyverse)
http://lubridate.tidyverse.org/
https://rpubs.com/davoodastaraky/lubridate
https://www.r-statistics.com/2012/03/do-more-with-dates-and-times-in-r-with-lubridate-1-1-0/
Date 타입을 더 쉽게 다루기 위한 팩키지
String -> Datetime
여러형태의 string형식으로 표현된 날짜데이터를 Date형식으로 parsing할수 있다. 일관된format의 Date타입의 날짜시간데이터를 얻을 수 있다.
또한 Date형식의 데이터에서 필요한 요소를 추출할 수도 있다.
ymd_hms()
> "2016-08/10" %>% class() # [1] "character"
> ymd("2016-08/10") %>% class() # [1] "Date"
> mdy("8.19.16")
[1] "2016-08-19"
> mdy("September 12, 2001")
[1] "2001-09-12"
> "1995-08-19 14:00:00" # [1] "character"
> specialDay <- ymd_hms("1995-08-19 14:00:00", tz="Asia/Seoul") # [1] "POSIXct" "POSIXt"
[1] "1995-08-19 14:00:00 KST"
> with_tz(specialDay, tzone='America/Los_Angeles') # [1] "POSIXct" "POSIXt"
[1] "1995-08-18 22:00:00 PDT"
Datetime -> String
year, month, day….
y <- year(now()) m <- month(now()) d <- day(now())
> specialDay <- ymd_hms("1995-08-19 14:00:00", tz="Asia/Seoul") # [1] "POSIXct" "POSIXt"
[1] "1995-08-19 14:00:00 KST"
# second(), minute(), hour(), day(), wday(), yday(), week(), month(), year(), tz()
> month(specialDay) # [1] "numeric"
[1] 8
> wday(specialDay, label=TRUE) # [1] "ordered" "factor"
[1] Sat
Levels: Sun < Mon < Tue < Wed < Thu < Fri < Sat
Datetime -> Datetime
Round, floor and ceiling methods
https://rdrr.io/cran/lubridate/man/round_date.html
x <- ymd_hms("2006-08-19 12:01:59.63")
round_date(x, "second") #"2006-08-19 12:02:00 UTC"
floor_date(x, "second") #"2006-08-19 12:01:59 UTC"
ceiling_date(x, "second") #"2006-08-19 12:02:00 UTC"
x <- ymd_hms("2006-08-19 12:08:31")
round_date(x, "minute") #"2006-08-19 12:09:00 UTC"
round_date(x, "5 mins") #"2006-08-19 12:10:00 UTC" 
