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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222
13
章
lubridate
による日付と時刻
(today() %--% next_year) %/% days(1)
#> [1] 365
13.4.4
まとめ
duration
,
period
,
interval
のどれをどのように使うべきでしょうか。いつものことですが、問題
を解決する最も単純なデータ構造を選ぶべきです。物理的な時間だけが必要なら、
duration
を使い
ます。人間の時間に合わせるなら、
period
を使います。タイムスパンの長さを人間の単位で表す必
要があれば、
interval
を使います。
図13-1に、異なるデータ型で可能な算術演算をまとめます。
図13-1 日付時間クラス間で可能な算術演算
1.
months()
があるのに
dmonths()
がないのはなぜか。
2. R を学び始めたばかりの人に
days(overnight * 1)
を説明する。どのように計算するか。
3. 2015年の毎月の初日を与える日付ベクトルを作りなさい。今年の毎月の初日を与える日付ベク
トルを作りなさい。
4. （日付で）誕生日を与えると何歳かを年で返す関数を書きなさい。
5.
(today() %--% (today() + years(1)) /months(1)
はなぜうまく働かないのか。
13.5
タイムゾーン
タイムゾーンは、地政学上のエンテイティとの相互作用があるので非常に複雑なテーマです。幸
い、データ分析ではそれほど重要ではないので、あまり詳細に立ち入る必要はありません。しかし、
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O’Reilly covers everything we've got, with content to help us build a world-class technology community, upgrade the capabilities and competencies of our teams, and improve overall team performance as well as their engagement.Julian F.
I wanted to learn C and C++, but it didn't click for me until I picked up an O'Reilly book. When I went on the O’Reilly platform, I was astonished to find all the books there, plus live events and sandboxes so you could play around with the technology.Addison B.
I’ve been on the O’Reilly platform for more than eight years. I use a couple of learning platforms, but I'm on O'Reilly more than anybody else. When you're there, you start learning. I'm never disappointed.Amir M.
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.