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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207
13
章
lubridate
による日付と時刻
13.1
はじめに
本章では、日付や時刻をR でどう扱うかを示します。一見したところは、日付も時間も単純です。
日常生活でいつも使っていますし、問題が生じることもありません。しかし、日付や時刻について深
く学べば学ぶほど、複雑になっていきます。手始めに、次の簡単そうな問題に答えてみましょう。
●
1年はいつも365日か。
●
1日はいつも24時間か。
●
1分はいつも60秒か。
すべての年が365日ではないことは知っていると思いますが、うるう年の完全な規則を知ってい
るでしょうか（3つの部分から構成されている）。世界中の多くの地域で夏時間（Daylight Saving
Time, DST）が採用されており、日によっては1日が23時間あるいは25時間となることは知ってい
るでしょう。地球の自転が徐々に遅くなっていることにより時々うるう秒が入るため、1分が61秒と
なるこ
とがあることは知らないかもしれません。
日付と時刻は、2 つの物理現象（地球の自転と公転）と暦月、タイムゾーン、DSTといった地政学
的現象との間で整合性をとらなければならないので、簡単に扱うことができません。本章だけで、日
付や時刻の詳細がすべてわかるわけではありませんが、データ分析業務で役立つ実用的なスキルの
基本が確実に得られます。
13.1.1
用意するもの
本章では、R で日付や時刻を扱いやすくする
lubridate
パッケージに焦点を絞ります。日付や時刻
を扱うときだけ必要なので、 ...
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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.