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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128
6
章 クラス分類
II
：感情分析
6.4.3
分類器のパラメータを調整する
私たちは分類器のセットアップ（初期化時のパラメータの調整など）について十分に探索できていま
せん。それついては時間をとって探索すべきです。分類器のセットアップについては、大きく分けて次
の2つが調整できる領域です。それは
TfidfVectorizer
と
MultinomialNB
です。最適なパラ
メータについて直感的なアイデアはないので、いくつかのパラメータの値を割り当てることにしましょ
う。
●
TfidfVectorizer
• NGramsについて次の場合を試します：ユニグラム (1,1)、バイグラム (1,2)、トライグラム
(1,3)
•
min_df
については、
1
または
2
の場合を試します。
• TF-IDFにおけるIDFの影響を検証するため、
use_idf
と
smooth_idf
について
False
と
True
の場合を試します。
•
stop_words
に
English
または
None
を設定し、ストップワードを用いる場合と用いない
場合を検証します。
• 単語の頻度（
sublinear_tf
）について対数を用いるかどうかを検証します。
• 記録する対象を単語の出現回数（頻度）か単語の出現の有無にするかを、
binary
を
True
または
False
にして試します。
●
MultinomialNB
・ スムージングについてを検証するため、
alpha
に次の値を設定します。
・ ラプラス・スムージング（1を足すスムージング）：
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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.