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(2020李宏毅)機器學習-Classification

文章目錄

  • ​​**Classification**​​
  • ​​抽象模組化​​
  • ​​**Two Boxes**​​
  • ​​**Two Classes**​​
  • ​​**Gaussian Distribution**​​
  • ​​**Probability from Class**​​
  • ​​**Maximum Likelihood**​​
  • ​​修改模型​​
  • ​​**Posterior Probability** (後驗機率)​​

Classification

(2020李宏毅)機器學習-Classification
(2020李宏毅)機器學習-Classification

抽象模組化

  • Function(Model)
  • (2020李宏毅)機器學習-Classification
  • Loss Function
  • (2020李宏毅)機器學習-Classification
  • Find the best function:
  • eg.perceptron,SVM

Two Boxes

(2020李宏毅)機器學習-Classification

Two Classes

Estimating the Probabilities From training data

(2020李宏毅)機器學習-Classification

Given an , which class does it belong to(來自于Class1的機率)

Generative Model

Gaussian Distribution

(2020李宏毅)機器學習-Classification

Probability from Class

Assume the points are sampled from a Gaussian distribution

Find the Gaussian distribution behind them

Maximum Likelihood

We have the “Water” type Pokémons:

We assume generate from the Gaussian

均值和方差如何求,參考我的博文多元高斯分布的最大似然估計

(2020李宏毅)機器學習-Classification
(2020李宏毅)機器學習-Classification
but 隻有54% accuracy …

修改模型

(2020李宏毅)機器學習-Classification
準确度提升:
(2020李宏毅)機器學習-Classification

Posterior Probability (後驗機率)

其中,
(2020李宏毅)機器學習-Classification

數學推導:

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抽象化:

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