May 2018
Intermediate to advanced
228 pages
4h 11m
Japanese
Content preview from Rによるテキストマイニング ―tidytextを活用したデータ分析と可視化の基礎
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2
■
1
章 整理テキスト形式
タ形式に保つことを求めてはいません。
tidytext
には、
tm
（
Feinerer et al. 2008
）、
quanteda
（
Benoit and Nulty 2016
）などの広く使われている
R
のテキストマイニング
パッケージが出力するオブジェクトを整理する関数（
broom
パッケージ
[Robinson,
既出
]
参照）が含まれています。そのため、たとえば
dplyr
などの整理ツールでデー
タをインポート、フィルタリング、処理してからデータを
DTM
（文書
-
単語行列）
に変換し、機械学習アプリケーションで処理するというワークフローを実現できま
す。このようにして得られたモデルは、再び整理形式に変換すれば、
ggplot2
で解釈
し、可視化することができます。
1.1
整理テキストとほかのデータ構造の比較
先ほど述べたように、整理テキスト形式は 1 行に 1 トークンの表であると定義し
ました。テキストデータをこの形式にまと
めれば、整理データ原則に従うことにな
り、一連の整理ツールで操作できるようになります。テキストマイニングのアプ
ローチでよくテキストが格納される形式と整理テキスト形式を比較することには意
味があります。
文字列
もちろん、
R
ではテキストを文字列（すなわち文字ベクトル）として格納す
ることができます。そして、テキストデータをまずこの形式でメモリに読
み込むことが多いでしょう。
コーパス
この形式のオブジェクトは、一般に未加工の文字列にメタデータや詳細情
報のアノテーション ...
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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.