May 2018
Intermediate to advanced
228 pages
4h 11m
Japanese
Content preview from Rによるテキストマイニング ―tidytextを活用したデータ分析と可視化の基礎
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.
166
■
8
章 ケーススタディ：
NASA
メタデータのマイニング
図8-5
選ばれた一部のキーワードを持つデータセットに含まれる単語の中でtf-idfが高いもの
tf-idf
を使ったため、個々のキーワードに対応する説明フィールドで最も重要な
単語を探し出すことができました。たとえば、「
SEISMOLOGY
」（地震学）をキー
ワードとするデータセットでは「
earthquake
」、「
risk
」、「
hazard
」（危険）、「
HUMAN
HEALTH
」（人間の健康）をキーワードとするデータセットでは「
wellbeing
」（健康）、
「
vulnerability
」（脆弱性）、「
children
」といった単語が含まれています。英単語ではな
い文字の組み合わせは、頭字語（たとえば、
Office of Management and Budget:
アメ
リカ合衆国行政管理予算局を表す
OMB
など）やそのトピックで重要な意味を持つ年
などの数値です。
tf-idf
統計量は、目的通りの単語、
すなわち文書のコレクションの
一部となっている文書にとって重要な単語を探し出したのです。
8.4
トピックモデリング
統計指標として
tf-idf
を計算したので、
NASA
メタデータ説明フィールドの内容が
どのようなものかについてすでにある程度のイメージはできていますが、
NASA
説
明フィールドとは何なのかという問いに別の方法でアプローチしてみましょう。第
6
章で説明したトピックモデリングを使えば、個々の文書（説明フィールド）をト
ピックの混合 ...
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.