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
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,
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.
133
5.6 情報理論の概要
この表をどう変換すれば、
seg
が
gt
を「どれほどよく表しているか」の指標になるでしょうか。
セグメンテーション処理は難問なので、出力結果と人間が手作業で生成した「正解データ」を比較
してセグメンテーションのアルゴリズムの性能を計るのは、大事なことなのです。
しかし、この比較も決して容易な作業ではありません。「自動化されたセグメンテーションが正
解データにどれくらい近いか」をいったいどう定義すればよいのでしょう。ここでは、情報変化
量、略して
VI
（
Meila, 2005
）と呼ばれる手法を紹介します。この手法は、次の質問の答えとして
定義されています。
1
つのセグメンテーションにおいて、あるピクセルのセグメント
ID
が与えら
れたら、もう一方のセグメンテーションにおけるそのピクセルの
ID
を判定するのに、平均してさ
らにどれだけ多くの情報が必要でしょうか。
直観的には、
2
つのセグメンテーションがそっくりなら、片方のセグメント
ID
を知ればもう片
方のセグメント
ID
がわかり、情報量は増えません。しかし、セグメンテーション間の差が大きく
なると、片方の
ID
がわかっていても、他の情報がなければ、もう一方の
ID
はわかりません。
5.6
情報理論の概要
この問いに答えるためには、情報理論入門が必要になります。ここでは簡単な紹介しかでき
ませんが、さらに詳しく知りたいなら、
Christopher Olah
のすばらしいブログ記事「
Visual
Information Theory
」（視覚情報理論、
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,
and much more.
Read now
Unlock full access
More than 5,000 organizations count on O’Reilly
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.