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👀 Seasonal Dummy Variables

由日期或時間特徵造出來的one-hot encoding (也就是把這些資料用0和1區分)

為了避免dummy variable trap (也就是有變數相依於其他變數)，會產生需要的變數量少一個的變數

seasonality_dummy2.jpg

優點:

  1. 適用在線性模型
  2. 可以(線性模型)分別預測各個季節性數值的影響
  3. 克服了在時間和日期數值不連續的問題

缺點:

引進很多額外特徵

seasonality_dummy3jpg.jpg

seasonality_dummy4.jpg

範例程式

Seasonal dummy features to capture seasonality

💭 Fourier Features

週期: 重複一個樣式的最小時間

頻率: 每單位時間會重複樣式的比例，為週期的倒數