Ask/Poll News.YC: What is a good open source Bayes classifier?

Re:Ask/Poll News.YC: What is a good open source Bayes classi... by jackbard on Tuesday February 26, 2008 @04:03PM (#124141)

http://www.codeproject.com/KB/cs/BayesClassifier.aspx

This is a simple one built in C#/.Net. I fixed a significant bug and raised classification accuracy from 74% -> 96% in my noisy dataset (automobile accident claims). I emailed the author with a bunch of improvements (such as histograms) and some other tweaks but never heard back. Anyway, the bugfix is simple: take a look at category.cs. In TeachPhrase(), move m_TotalWords++ inside the test for "if (!m_Phrases.TryGetValue(phrase, out pc))".

What you want here is to count the # of unique words. The original code was counting the total # of times all words appear.This one change reduced classification errors by 3X.

Cheers, --Jack

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Re:Ask/Poll News.YC: What is a good open source Bayes classi... by jackbard on Tuesday February 26, 2008 @04:09PM (#124150)

Oh, forgot to mention that you'll want to compute probabilities using logarithms to avoid underflow precision loss (which will introduce classification errors). example: wordValue = System.Math.Log((double)count / (double)cat.TotalWords);

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