Working with Dates

String Simple

d1 = date()
d1

## [1] "Tue Mar 24 16:39:47 2015"

class(d1)

## [1] "character"

d2 = Sys.Date()
d2

## [1] "2015-03-24"

class(d2)

## [1] "Date"

Formatting Dates

format(d2,"%a %b %d")

## [1] "화 3 24"

Sys.getlocale()

## [1] "LC_COLLATE=Korean_Korea.949;LC_CTYPE=Korean_Korea.949;LC_MONETARY=Korean_Korea.949;LC_NUMERIC=C;LC_TIME=Korean_Korea.949"

Sys.setlocale("LC_TIME", "C")

## [1] "C"

format(d2,"%a %b %d")

## [1] "Tue Mar 24"

Sys.setlocale("LC_TIME", "Korean_Korea")

## [1] "Korean_Korea.949"

format(d2,"%a %b %d")

## [1] "화 3 24"

Creating Dates

Sys.setlocale("LC_TIME", "C")

## [1] "C"

x = c("1jan1960","2jan1960","31mar1960","30jul1960");z = as.Date(x,"%d%b%Y")
z

## [1] "1960-01-01" "1960-01-02" "1960-03-31" "1960-07-30"

z[1] - z[2]

## Time difference of -1 days

as.numeric(z[1] - z[2])

## [1] -1

Convering to Julian

weekdays(d2)

## [1] "Tuesday"

months(d2)

## [1] "March"

julian(d2)

## [1] 16518
## attr(,"origin")
## [1] "1970-01-01"

#attr(,"origin")

Lubridate

library(lubridate); ymd("20140108")

## [1] "2014-01-08 UTC"

mdy("08/04/2013")

## [1] "2013-08-04 UTC"

dmy("03-04-2013")

## [1] "2013-04-03 UTC"

ymd("2015-03-23")

## [1] "2015-03-23 UTC"

ymd_hms("2015-03-23 11:43:12")

## [1] "2015-03-23 11:43:12 UTC"

ymd_hms("2015-03-23 11:43:12", tz="Asia/Seoul")

## [1] "2015-03-23 11:43:12 KST"