choose the best class if 2 class have same P (c|d), naive bayes

Posted by ryandi on Stack Overflow See other posts from Stack Overflow or by ryandi
Published on 2014-06-06T08:48:48Z Indexed on 2014/06/06 9:25 UTC
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classification

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data-mining

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text-mining

Hello I have some question about naive bayes classifier . In my project I have to classify a text into a class from 4 available class.

In naive bayes we have formula like

cmap=argmax.P(d|c).P(c)

I have standarize the amount of training document of each class, so I got a same P(c) value for each class (0.25).

Here's my question: What if a testing document token doesn't have any token which belong to any of those 4 class(in document training)?

Resulted to all of the class have same value of P(d|c).P(c). Which class should i pick?

What if the token exist, and 2 class or more have same value of P(d|c).P(c) what should I do?

Thank you..

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