difftime(time1, time2, tz,
units = c("auto", "secs", "mins", "hours",
"days", "weeks")) # 轉換成毫秒、秒、分鐘、小時、天、周
as.difftime(tim, format = "%X", units = "auto") # 數值換成日期
as.numeric(tim, units = "days") # 日期轉換成數值
可執行案例一：
(z <- Sys.time() - 3600)
Sys.time() - z # just over 3600 seconds.
## time interval between release days of R 1.2.2 and 1.2.3.
ISOdate(2001, 4, 26) - ISOdate(2001, 2, 26)
as.difftime(c("0:3:20", "11:23:15"))
as.difftime(c("3:20", "23:15", "2:"), format = "%H:%M") # 3rd gives NA
(z <- as.difftime(c(0,30,60), units = "mins"))
as.numeric(z, units = "secs")
as.numeric(z, units = "hours")
format(z)
案例二
tim=difftime(data_a$date[3],data_a$date[2],units="days")
as.difftime(tim, format = "%X", units = "days")
as.numeric(tim, units = "days")
