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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37
3
章
dplyr
によるデータ変換
3.1
はじめに
可視化は洞察を進める上で重要なツールですが、データが必要な形式で手に入ることは稀です。
多くの場合、新たな変数を作る、要約をする、変数の名前を変える、データの順序を変えるなどして、
作業をしやすくする必要があります。これらすべて（とさらに多くのこと）をどうすればよいかを本
章で学びます。
dpylr
パッケージと2013年にニューヨークを飛び立ったフライトのデータセットを
用いてデータ変換について学習します。
3.1.1
準備するもの
本章では、
ggplot2
と並んで
tidyverse
の重要な要素である
dpylr
パッケージの使い方に焦点を当
てます。
nycflights13
パッケージのデータを用いて主なアイデアを示し、
ggplot2
を使ってデータ
を理解します。
library(nycflights13)
library(tidyverse)
tidyverse
をロードしたときに出る「Conflicts」というメッセージは、注意してメモしておくこと。
これは
dpylr
がR の基本関数を上書きしていることを示しています。
dpylr
ロード後にこれらの関数
の基本版を使いたい場合は、
stats::filter()
や
stats::lag()
のように完全名を使う必要がありま
す。
3.1.2
nycflights13
dplyr
における基本データ操作を調べるために、
nycflights13::flights
を使います。このデータ
フレームは、2013 年にニューヨークを
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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.