結果が得られず, 未知のデータに対応できなくなっている. • 単純に考えると特徴量が1つ増えるにつれ, 必要なデータ数は2倍, 4倍, 8倍...... One-Hotエンコーディングによる不安定性 • 数値データ以外を扱い, フラグを記述するために特徴量が⼀つ必要なOne-Hotエ ンコーディングは, 同じ問題に対して妥当なモデルが複数存在して係数が⼀意に 定まらず, それが結果の解釈の妨げとなることがある[7]. • 前述の例のように, ⾚⾊, ⻩⾊, 緑⾊のフラグなどの数値ではない変数(カテゴリ 変数と呼ばれる)はむやみに使うと機械学習の能⼒が低下する [7] Michel Verleysen and Damien Francois. 2005. The Curse of Dimensionality in Data Mining and Time Series Prediction. [8] Alice Zheng and Amanda Casari. 2019. Feature Engineering for Machine Learning: Principles and Techniques for Data Scientists. 19 15
Learning, Springer. [2] J.R. Quinlan. 1986. “Induction of Decision Trees.” [3] Lior Rokach and Oded Maimon. 2005. Data Mining and Knowledge Discovery Handbook, Springer, p166. [4] Andy Liaw and Matthew Wiener. 2002. “Classification and Regression by randomForest.” [5] Will Koehrsen. 2017. Random Forest Simple Explanation (https://medium.com/@williamkoehrsen/random-forest-simple-explanation-377895a60d2d ) [6] M. Metghalchi, J. Marcucci and Y. Chang. 2012. "Are moving average trading rules profitable? Evidence from the European stock markets.” [7] Michel Verleysen and Damien Francois. 2005. The Curse of Dimensionality in Data Mining and Time Series Prediction. [8] Alice Zheng and Amanda Casari. 2019. Feature Engineering for Machine Learning: Principles and Techniques for Data Scientists. [9] 村瀬さんのスライド (Retrieved from https://python-algo.connpass.com/event/128511/presentation/ https://python-algo.connpass.com/event/128513/presentation/ ) [1] Bishop, C. M. 2006. Pattern Recognition and Machine Learning, Springer. [2] J.R. Quinlan. 1986. “Induction of Decision Trees.” [3] Lior Rokach and Oded Maimon. 2005. Data Mining and Knowledge Discovery Handbook, Springer, p166. [4] Andy Liaw and Matthew Wiener. 2002. “Classification and Regression by randomForest.” [5] Will Koehrsen. 2017. Random Forest Simple Explanation (https://medium.com/@williamkoehrsen/random-forest-simple-explanation-377895a60d2d ) [6] M. Metghalchi, J. Marcucci and Y. Chang. 2012. "Are moving average trading rules profitable? Evidence from the European stock markets.” [7] Michel Verleysen and Damien Francois. 2005. The Curse of Dimensionality in Data Mining and Time Series Prediction. [8] Alice Zheng and Amanda Casari. 2019. Feature Engineering for Machine Learning: Principles and Techniques for Data Scientists. [9] (Retrieved from https://python-algo.connpass.com/event/128511/presentation/ https://python-algo.connpass.com/event/128513/presentation/ ) 23 18