October 2017
Intermediate to advanced
480 pages
9h 49m
Japanese
Content preview from Rではじめるデータサイエンス
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218
13
章
lubridate
による日付と時刻
13.4
タイムスパン
次に、減法、加法、除法を含めた算術が日付にどう作用するかを学びます。タイムスパンを表す3
つの重要なクラスもついでに学びます。
●
duration
は正確に秒数で表す。
●
period
は週や月のような人が使う単位で表す。
●
interval
は開始点と終了点で表す。
13.4.1
duration
（期間）
日付の間の差をとると、Rでは
difftime
オブジェクトになります。
# Hadley
は何歳か
?
h_age <- today() - ymd(19791014)
h_age
#> Time difference of 13511 days
difftime
クラスオブジェクトは、タイムスパンを秒、分、時、日、週のいずれかで表します。単
位が異なるのは後々問題の原因になるので、
lubridate
では常に秒で表す
duration
を代わりに用意
しました。
as.duration(h_age)
#>
[1] "1167350400s (~36.99 years)"
duration
には便利なコンストラクタがたくさんあります。
dseconds(15)
#> [1] "15s"
dminutes(10)
#> [1] "600s (~10 minutes)"
dhours(c(12, 24))
#> [1] "43200s (~12 hours)" "86400s (~1 days)"
ddays(0:5)
#> [1] "0s" "86400s (~1 ...
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I'm always learning. So when I got on to O'Reilly, I was like a kid in a candy store. There are playlists. There are answers. There's on-demand training. It's worth its weight in gold, in terms of what it allows me to do.