October 2014
Intermediate to advanced
288 pages
6h 27m
Japanese
Content preview from 実践 機械学習システム
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.
4.3
トピックの数を選択する
81
最も記述の少ないのは、「中央アフリカのフランス植民地」についてのようです（図4-5）
†
。全体の
1.5％の文書だけが、そのトピックについて触れており、それは全体の単語の0.08％です。フランス語
のWikipediaを対象に、同様なトピックモデルを行うと、おそらく結果は異なるものになるでしょう。
4.3
トピックの数を選択する
これまでトピックの数は100に固定していました。しかし、この100という数字には、特に意味はな
く、恣意的に決めた値です。トピックの数は、20でも200でも構いません。幸いにも、多くの人にとっ
ては、この数字はそれほど重要ではないでしょう。先ほど見てきたように、トピックを中間的な要素と
してだけ用いる場合、トピックの数が最終的なシステムに与える影響はほとんどありません。これが意
味することは、100や200ぐらいの十分に大きなトピック数であれば、レコ
メンドシステムの結果はさ
ほど変わらない、ということです。一つの基準として、設定する値は100ぐらいが良いでしょう（20ぐ
らいでは一般的な文書を扱う場合、少なすぎます）。これはパラメータの
alpha
の値を設定する場合
も同じです。
alpha
の値をいろいろ変えてトピックの結果を見ることはできますが、最終的な結果は
あまり変わりません。
トピックモデリングを中間的なツールとして用いることが多くあります。そのような場合、パ
ラメータの微調整はそれほど重要ではありません。トピックの数や
alpha
などのパラ
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.