November 2018
Intermediate to advanced
272 pages
6h 51m
Japanese
book
エレガントなSciPy ―Pythonによる科学技術計算
by Juan Nunez-Iglesias, Stéfan van der Walt, Harriet Dashnow, 山崎 邦子, 山崎 康宏
Content preview from エレガントなSciPy ―Pythonによる科学技術計算
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190
8 章 Toolz を使って小さなノートパソコンでビッグデータを処理する方法
た。
Toolz
の構成要素により、ストリーミング用のプログラムを非常にエレガントに書けるように
なるので、本書の準備段階で
Toolz
に関する章を抜きにすることは考えられませんでした。
ここで、本章で言う「ストリーミング」の定義と、ストリーミングをする価値がある理由を明ら
かにしたいと思います。仮に、テキストファイルのデータがあり、値の
log(x + 1)
の列ごとの平均
値を求めたいとします。一般的な方法は、
NumPy
を使って値を読み込み、行列のすべての値の対
数関数を計算し、それから第
1
軸の平均値を取る以下のようなものでしょう。
import numpy as np
expr = np.loadtxt('data/expr.tsv')
logexpr = np.log(expr + 1)
np.mean(logexpr, axis=0)
array([ 3.11797294, 2.48682887, 2.19580049, 2.36001866, 2.70124539,
2.64721531, 2.43704834, 3.28539133, 2.05363724, 2.37151577,
3.85450782, 3.9488385 , 2.46680157, 2.36334423, 3.18381635,
2.64438124, 2.62966516, 2.84790568, 2.61691451, 4.12513405]) ...
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and much more.
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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.