July 2022
Intermediate
440 pages
11h 58m
Japanese
Content preview from Pythonで動かして学ぶ！あたらしい機械学習の教科書 第3版
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234
)
cont.clabel(fmt="%.2f", fontsize=8)
plt.xlabel("$w_0$", fontsize=14)
plt.ylabel("$w_1$", fontsize=14)
plt.grid()
plt.show()
# 実行結果は図 6.7 を参照
リスト 6-1-(6) を実行すると図 6.7 に示したグラフが表示されます。
ロジスティック回帰モデル
平均交差エントロピー誤差関数
等高線表示
この辺に最小値がありそう
E
(w)：
w
0
w
1
w
0
w
1
図 6.7：ロジスティック回帰モデルの平均交差エントロピー誤差関数
平均交差エントロピー誤差関数は、風呂敷の対角の隅を持って持ち上げたような形
をしていました。どうやら最小値は、
、 の付近にありそうです。
学習則の導出
6.1.6
さて、交差エントロピー誤差が最小になるパラメータの解析解は求めることができ
ません。
が非線形のシグモイド関数を含んでいるからです。そこで、勾配法を使
って数値的に求めることを考えます。勾配法を使うには、パラメータの偏微分が必要
でした。
それでは、式 6-17 の平均交差エントロピー誤差
を で偏微分したものを
Out
217-262_ch06.indd 234217-262_ch06.indd 234 2022/06/21 19:032022/06/21 19:03
235
6
求めていきましょう。まず、式 6-17 を式 6-18 のように表します。
上記の和の中身は式 6-19 のように定義しました。
微分と和は交換できることから ...
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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.
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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.