日時の差の計算

Rで扱う日付と時刻

Charlotte Wickham

Instructor

日時の算術演算

  • datetime_1 - datetime2: 経過時間の減算
  • datetime_1 + (2 * timespan): 過去・未来の日時を生成する加算と乗算
  • timespan1 / timespan2: 単位変換のための除算
Rで扱う日付と時刻

日時の減算

releases <- read_csv("rversions.csv")
last_release <- filter(releases, date == max(date))

Sys.Date() - last_release$date

Time difference of 99 days

difftime(Sys.Date(), last_release$date)

Time difference of 99 days

time1 - time2 は difftime(time1, time2) と同じです

Rで扱う日付と時刻

difftime()

units = "secs", "mins", "hours", "days", または "weeks"

difftime(Sys.Date(), last_release$date, units = "secs")

Time difference of 8553600 secs

difftime(Sys.Date(), last_release$date, units = "weeks")

Time difference of 14.14286 weeks
Rで扱う日付と時刻

now() と today()

today()

"2017-10-07"

str(today())

 Date[1:1], format: "2017-10-07"

now()

"2017-10-07 09:44:52 PDT"

str(now())

 POSIXct[1:1], format: "2017-10-07 09:44:59"
Rで扱う日付と時刻

練習しましょう！

Rで扱う日付と時刻

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