August 2017
Intermediate to advanced
500 pages
12h 3m
Japanese
Content preview from PythonとJavaScriptではじめるデータビジュアライゼーション
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123
5.5 データのスクレイピング
5.5.3
初めてのスクレイピング
requests
と
BeautifulSoup
があるので、ノーベル賞の全受賞者の名前、年、分野、国籍を取
得する小さなタスクに取り組んでみましょう。
Wikipedia
のノーベル賞メインページ（
http://
en.wikipedia.org/wiki/List_of_Nobel_laureates
）から始めます。スクロールダウンすると年と分野
ごとの全受賞者を示すテーブルがあります。このテーブルは最低限のデータ要件を満たしています。
Web
スクレイピングには何らかの
HTML
エクスプローラが必要です。ここでは、
Chrome
の
Web
デベロッパーの
Elements
タブを使います（「
4.5.1
Elements
タブ」を参照）。図
5-1
は、
Web
ページの構造を知るために必要な主な要素を表しています。関心のあるデータ（この場合
は
Wikipedia
のテーブル）を選び、ページのその他の要素は避ける方法を知る必要があります。
適切な選択パターンを作成することが効果的なスクレイピングの鍵で、要素インスペクタを使っ
て
DOM
要素をハイライトすると、
CSS
パターンと（右クリックで）
xpath
の両方がわかりま
す。
xpath
は
DOM
要素選択のための効果的な構文で、高性能なスクレイピングソリューション
Scrapy
の基盤となっています。■
A
C
B
D
図
5-1
Wikipedia
のノーベル賞に関するメインページ。
A
と
B
はウィキテーブルの
CSS
セレクタを表す。右ク ...
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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.