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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262
16
章 ベクトル
16.4
アトミックベクトルを使う
アトミックベクトルにはどんな種類があるかわかったでしょうから、これらを扱うツールで重要な
ものをまとめておくと便利です。次のようなものがあります。
●
型をどのようにして変換するか、自動的に行われるのはいつか。
●
オブジェクトがどの型のベクトルか、どうすればわかるか。
●
異なる長さのベクトルを処理するときには、何が起こるか。
●
ベクトルの要素にどのようにして名前を付けるか。
●
目的の要素をどのように取り出すか。
16.4.1
型強制
ある型のベクトルから別の型のベクトルへ変換あるいは型強制するには2 つの方法があります。
●
明示的型強制は、
as.logical()
,
as.integer()
,
as.double()
,
as.character()
のような関数を
呼び出したときに起こる。明示的型強制を使うときには、ベクトルの中に間違った型が絶対にな
いようにして、元の提
供者に戻せるかどうか常にチェックすべきだ。例えば、
readr col_types
の指定を変更する必要があるかもしれない。
●
暗黙型強制は、ある種のベクトルを期待する文脈において、ベクトルを使うときに起こる。例え
ば、数値要約関数に論理ベクトルを使うとか、整数ベクトルが予期されるところで実数ベクトル
を使うときである。
明示的型強制を使うことは比較的稀で、わかりやすいので、本節では、暗黙型強制に焦点を絞り
ます。
数値処理の文脈で論理ベクトルを使う際の暗黙型強制の ...
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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.