June 2024
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Content preview from Python2年生 データ分析のしくみ 第2版 体験してわかる！会話でまなべる！
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83
データを平らに均（なら）す
LESSON
08
Aクラス = 85.0
B
クラス = 80.0
それぞれが、1つの数値で表現されるので、わかりやすくなりました。
この結果を見ると、「
Aクラスは全体として85点、Bクラスは全体として80点なんだなあ」
とわかります。
Aクラス Bクラス
0 82 100
1 89 62
2 93 82
3 85 70
4 76 86
85.0 80.0
df["A
クラス"].mean() df["Bクラス"].mean()
代表値は 、「 デ ー タ の 比較」に使う
このようにして求めた代表値は、「データの比較」に使います。
代表値は
1つの値なので、1つだけでは「何を意味するのか」は、よくわかりません。「他
の値と比較」することで初めて意味が見えてきます。
例えば、「代表値と、代表値を比較」すると
「グループとグループの差」がわかります。
「
Aクラスと、Bクラスの差」がわかるのです。
「
Aクラス」と「Bクラス」の平均値をもう一度表示させてみましょう。今度は、別の方
法で表示させてみましょう（リスト
3.3）。データフレーム自体に命令します。すると、デー
タフレームの中の各列の平均値が表示されます。
出力結果
A
クラスと
B
クラスの
平均が、パッと見てわ
かるようになったね。
Chapter
3
84
•
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