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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B.2
オペレーティングシステムとの連携
529
ます。
In [30]: eval(_i27)
Out[30]: 'bar'
ここで
_i27
はコード入力の
In [27]
に相当します。
IPython
には、入出力履歴を制御できるマジック関数が用意されています。
%hist
は入力履歴の全
体、あるいは一部を表示します。このとき、行番号付き、もしくは行番号なしを選択できます。
%reset
は対話名前空間をクリアします。このとき、入出力キャッシュも合わせてクリアすることができます。
%xdel
は特定のオブジェクトへの参照をすべて削除することができます。これらのマジック関数の詳細
についてはドキュメントを参照してください。
巨大なデータセットを扱っていて、
Python
標準の
del
キーワードなどで変数を削除するよう
な場合、
IPython
の入出力履歴機能はガベージコレクトされない（メモリ解放されない）こと
に注意してください。このような場面では、誤操作に留意しながら
%xdel
や
%reset
を活用す
ることで対処できる場合があることを覚えておいてください。
B.2
オペレーティングシステムとの連携
IPython
の重要な機能の
1
つに、オペレーティングシステム（
OS
）のシェルとの統合があります。とり
わけ有用なのは、
IPython
環境を終了せずに、基本的な
OS
コマンド操作を直接実行できる点です。具
体的には、シェルコマンドの実行、カレントディレクトリの変更、リストや文字列など
Python
オブジェ
クトへのシェルコマンド結果の格納 ...
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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.