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
Become an O’Reilly member and get unlimited access to this title plus top books and audiobooks from O’Reilly and nearly 200 top publishers, thousands of courses curated by job role, 150+ live events each month,
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.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.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.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.
195
12
章
forcats
でファクタ
12.1
はじめに
Rにおいてファクタは、固定した既知集合の可能値をとるカテゴリ変数の処理に使われます。ファ
クタは、文字列順以外で文字ベクトルを表示するにも役立ちます。
これまでの経緯では、ファクタは、文字よりも扱いが容易でした。結果として、基本 R の多くの関
数で、文字をファクタに自動変換していました。すなわち、本当に役立つところ以外でもファクタが
出現していました。
tidyverse
ではそういう心配はなく、ファクタが本当に役立つ場面に焦点を絞る
ことができます。
フ ァ ク タ に つ い て の 歴 史 的 な こ と に つ い て は、Roger Pengの「stringsAsFactors: An
unauthorized biography」（http://bit.ly/stringsfactorsbio）と Thomas Lumleyの「stringsAsFactors
= <sigh>」（ht
tp://bit.ly/stringsfactorsigh）を読むことを勧めます。
12.1.1
用意するもの
ファクタを扱うために、（
factors
のアナグラム（文字入れ替え）でもある）
forcats
パッケージを使
います。これにはカテゴリ変数を扱うツールが用意されています。ファクタを扱う広範囲のヘルパー
関数が含まれています。
forcats
は
tidyverse
に含まれていないので、明示的にロードする必要があ
ります。
library(tidyverse) ...
Become an O’Reilly member and get unlimited access to this title plus top books and audiobooks from O’Reilly and nearly 200 top publishers, thousands of courses curated by job role, 150+ live events each month,
and much more.
Read now
Unlock full access
More than 5,000 organizations count on O’Reilly
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.