October 2017
Intermediate to advanced
832 pages
13h 34m
Japanese
Content preview from Fluent Python ―Pythonicな思考とコーディング手法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,
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3章ディクショナリとセット
ユーザのプログラムコードが明示的にディクショナリを使用していないときでも、実行中のPythonプログラムは同時にアクティブなディクショナリをたくさん持っています。
——A. M. Kuchling『Beautiful Code』, 18章「Python's Dictionary Implementation」より[EN-09][JP-04]
dict型はプログラムで広く使用されるだけでなく、Pythonの基盤も構成しています。モジュールの名前空間、クラスとインスタンスの属性、関数のキーワード引数といった基盤的な構造はディクショナリで実装されています。組み込み関数は__builtins__.__dict__にあります。
重要な役割を担っているため、Pythonのdictは高度に最適化されています。Pythonの高性能dictの背後にあるエンジンはハッシュテーブルです。
本章ではセット（set）もカバーしますが、それはセットもハッシュテーブルで実装されているからです。ハッシュテーブルの仕組みを知ることで、ディクショナリとセットを最大限に活用できるようになります。
本章の概要は次のとおりです。
- 一般的なディクショナリメソッド
- 存在しないキーに対する特別な処理
- 標準ライブラリにある
dictのバリエーション set型およびfrozenset型- ハッシュテーブルの仕組み
- ハッシュテーブルの注意事項（キーの型の制限、予測できない順序など）
3.1 一般的なマップ型
collections.abcモジュールは、dictやこれに類似した型のインタフェースを形式化する抽象基底クラスであるMappingおよびMutableMappingを提供しています（Python 2.6から3.2では、これらのクラスは ...
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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.