July 2018
Intermediate to advanced
596 pages
13h 35m
Japanese
Content preview from Pythonによるデータ分析入門 第2版 ―NumPy、pandasを使ったデータ処理
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234
7
章 データのクリーニングと前処理
メソッド 説明
casefold
文字列内のアルファベット文字を小文字に変換する。その際に、地域固有の変種文
字（ダイアクリティカルマーク付きの文字やエスツェットなど）は、同等の標準アル
ファベット文字での表現に置き換える。
ljust, rjust
文字列が指定した幅以上になるように空白を詰める。その際に、文字列をそれぞれ
左揃えと右揃えにする。反対側の余ったスペースは空白文字（またはそれ以外の穴
埋め文字）で埋める。
7.3.2
正規表現
正規表現を用いると、（場合によってはかなり複雑な）文字列パターンを用いた、テキスト内での柔
軟な文字列検索やパターンマッチが可能になります。個々の正規表現（regexとも呼ばれます）は、正
規表現言語の文法に従って書かれた文字列です。正規表現を文字列に適用する役割を担っているのが、
Python
組み込みの
re
モジュールです。ここではその使い方の例をいくつか紹介しましょう。
正規表現を書くコツはそれだけでも
1
つの章になるようなテーマですので、この本の範疇を
超えています。インターネット上や他の書籍には素晴らしいチュートリアルやリファレンス
がたくさんありますので、それらを参照してください。
re
モジュールの関数は、パターンマッチング、文字列置換、文字列分割の
3
つのカテゴリに分類で
きます。当然ながら、これら
3
つはすべてつながっています。正規表現で文字列パターンを記述すると、
その文字列パターンに沿ってテキスト内で文字列の検索が行わ
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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.
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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.