March 2018
Beginner to intermediate
624 pages
16h 10m
Japanese
Content preview from Head First Python 第2版 ―頭とからだで覚えるPythonの基本
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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.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.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.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.
Python
の 辞 書 は サ イ ズ
変更可能なハッシュテー
ブルとして実装されてお
り、多くの状況に対して十
分最適化されています。そ
の結果、辞書の検索は高速
です。
辞書はかっこが好き
[]
を使った値の検索
辞書の角かっこはリストの場合と同様に機能します。しかし、インデックス値
を使って指定のスロットのデータにアクセスする代わりに、辞書では対応する
キーでデータにアクセスします。
前ページの最後に示したように、辞書の角かっこの中にキーを指定すると、イ
ンタプリタはそのキーに対応する値を返します。前述の例を再び検討し、この
考え方を頭に刻み込みましょう。
辞書検索は速い！
キーを使って辞書から値を抽出することが必要な状況はよくあるので、
Python
の辞書は便利です。例えば、プロフィールからのユーザ詳細の検索など
は、基本的に
person3
辞書に対してここで行っていることと同じです。
辞書の格納順は重要ではありません。重要な
ことは、インタプリタがキーと
関連のある値に（辞書がどんなに大きくなっても）素早くアクセスできることで
す。ありがたいことに、インタプリタは高度に最適化されたハッシュアルゴリ
ズムを採用しているおかげでこれが可能です。
Python
の多くの内部構造と同
様、ここでの細部の処理はすべてインタプリタに安心して任せて、辞書の機能
を利用できます。
100
3
章
キー
No4
オブジェクト
キー
No1
オブジェクト
キー
No3
オブジェクト
キー
No2
オブジェクト
辞書
性別
研究者
職業
ベテルギウス第
7
星
母星
フォード・プ
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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.