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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122
5 章 Python による Web からのデータの取得
の高度なデューイ十進分類法
†
で分類されるでしょう。熱心なデータ追求者にとって残念なこと
に、
Web
は有機的に増大し、大抵は新米データ可視化作成者のための簡単なデータアクセスを考
慮した制約を受けていません。そのため、実際には
Web
は巨大な量のデータのようなもので、整
形され利用可能なものもありますが（幸い、その割合は増えています）、その多くは人間が利用す
るには不適切な形式や設計になっています。そして人間は、このような比較的処理能力の低いマシ
ンで問題となる乱雑で不適切に整形されたデータをパースできます
‡
。
スクレイピングでは、パターンに従った希望のデータを入手して残りは放置します。運が良けれ
ば、データを含む
Web
ページに名前付きテーブルや汎用クラスより優先される特定の
ID
などの
便利なポインタがあります。運が悪ければこのようなポインタがなく、他のパターンを使うか、最
悪の場合にはメインの
div
の
3
番目のテーブルなど序数の指定子を用いなければいけません。こ
れは明らかに脆弱で、誰かが
3
番目のテーブルの上に新しくテーブルを追加したらおかしくなっ
てしまいます。
この節では、簡単なスクレイピングを試し、ノーベル賞受賞者データを取得します。
Python
で
このような軽量のスクレイピングに最適な
BeautifulSoup
を使い、高機能の
Scrapy
の説明は次章
に譲ります。
データや画像が Web 上にあるからといって、必ずしも自由に使ってよいわけではありません。本書で ...
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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.