October 2014
Intermediate to advanced
288 pages
6h 27m
Japanese
Content preview from 実践 機械学習システム
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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.
1.5
はじめての（簡単な）機械学習アプリケーション
19
図1-5
モデルを複雑にすればするほど、曲線はデータの複雑さを捉えているようです。誤差の値を見るこ
とでも、そのことがわかります。
Error d=1: 317,389,767.339778
Error d=2: 179,983,507.878179
Error d=3: 139,350,144.031725
Error d=10: 121,942,326.363461
Error d=100: 109,318,004.475556
しかし、得られた曲線を詳しく見てみると、「これらのモデルは、データを生み出している本当のプ
ロセスを正しく捉えているのか？」と疑問に思うことでしょう。言い換えると、「これらのモデルは、
webサイトを訪れる顧客の集団行動を正しく表現できているのか？」ということになります。多項式の
次数が
10
と
100
の場合を見ると、短い周期で振動するような曲線になっています。これはモデルが
データに適応しすぎて
いるようです。つまり、プロセスの本質を捉えているだけではなく、データに含
まれるノイズまでも捉えていることになります。このような振る舞いは過学習（overfitting）と呼ばれま
す。
この時点で、次に取るべき行動は、次の3つが考えられます。
先月のWebトラフィック量
時間
20
1
章
Python
ではじめる機械学習
●
多項式モデルからどれか一つを選択する
●
より複雑なモデル（スプライン曲線など）に切り替える
●
データについて別の視点
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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.