Linjiayu6/DL-BayesTheorem

[2019][Python/ Bayes / Naive Bayes Classifier]

[Bayes' Theorem]

[Reference]

• *https://www.python-course.eu/naive_bayes_classifier_introduction.php
• https://dzone.com/articles/naive-bayes-tutorial-naive-bayes-classifier-in-pyt
• https://www.zhihu.com/question/19725590
• https://www.youtube.com/watch?v=XQoLVl31ZfQ

1. What Is Naive Bayes?

• Naive Bayes is among one of the simplest,
• but most powerful algorithms for classification based on [Bayes' Theorem] with an assumption of independence among predictors

2. 现实生活中有什么用?

• 同样的，在现实世界中，我们每个人都需要预测。想要深入分析未来、思考是否买股票、政策给自己带来哪些机遇、提出新产品构想，或者只是计划一周的饭菜。
• 贝叶斯定理就是为了解决这些问题而诞生的，它可以根据过去的数据来预测出概率。
• Spam Filtering
• Medical Diagnosis
• Weather Prediction

3. What Is Bayes' Theorem?

• In statistics and probability theory, Bayes' theorem describes the probability of an event, based on prior knowledge of conditions that might be related to the event. It serves as a way to figure out conditional probability.

• 更好理解图

• 条件概率公式
• https://www.youtube.com/watch?v=ibINrxJLvlM
• P(A): prior probability
• P(B|A)/P(B): likelihood ratio

• 全概率公式

• 条件概率另一种写法

• 推导记录

在这里，如果"可能性函数"P(B|A)/P(B)>1，意味着"先验概率"被增强，事件A的发生的可能性变大；如果"可能性函数"=1，意味着B事件无助于判断事件A的可能性；如果"可能性函数" 小于1, 意味着"先验概率"被削弱，事件A的可能性变小。

4. 例子

• 水果糖问题 http://www.ruanyifeng.com/blog/2011/08/bayesian_inference_part_one.html
• Spam http://www.ruanyifeng.com/blog/2011/08/bayesian_inference_part_two.html

5. Naive Bayes Classifier

[Reference]

• https://www.python-course.eu/naive_bayes_classifier_introduction.php
• https://zh.wikipedia.org/wiki/%E6%9C%B4%E7%B4%A0%E8%B4%9D%E5%8F%B6%E6%96%AF%E5%88%86%E7%B1%BB%E5%99%A8

特征值分类, 预测概率
  cd /NaiveBayesClassifier
  python main.py