RE: [Classifier4j-devel] RE: Fwd: calculateOverallProbability Que stio ns

[Nick L. <nl...@es...>]

If that works better for you, then do it. 

I'd suggest something like (untested!):

public class YourClassifier extends BayesianClassifier {
	protected double calculateOverallProbability(WordProbability[] wps)
{
		if (wps == null || wps.length == 0) {
			return IClassifier.NEUTRAL_PROBABILITY;
		} else {
			return
super.calculateOverallProbability(WordProbability[] wps);
		}
	}
}

The classifier heirachy is designed to be extended like that.

Nick


> -----Original Message-----
> From: David Spencer [mailto:dav...@ya...]
> Sent: Friday, 10 September 2004 4:29 AM
> To: cla...@li...
> Subject: [Classifier4j-devel] RE: Fwd: calculateOverallProbability
> Questio ns
> Importance: Low
> 
> 
> I just stumbled across this thread from last year:
> 
> http://sourceforge.net/mailarchive/forum.php?thread_id=3483166
> &forum_id=34026
> 
> I'm having similar "troubles" in the sense that classify() is 
> returning
> 0.99 too often and it's because some of the words either have zero
> matches or zero non-matches.
> 
> The question is, does it make sense to ignore words that don't have at
> least 1 match and at least 1 non-match?
> 
> It's easy enough to extend BayesianClassifier and override
> calculateOverallProbability() and in my experiment it seems to work
> "better", though I guess you could argue it's not fair to ignore such
> words, as maybe a given word will always be a match or non-match such
> it should be considered somehow.
> 
> Anyway the code mode I did was at the bottom here of this fragment -
> just added 2 lines:
> 
> 	protected double 
> calculateOverallProbability(WordProbability[] wps)
> 	{
>         if (wps == null || wps.length == 0)
> 		{
>             return IClassifier.NEUTRAL_PROBABILITY;
>         }
> 		else
> 		{
>             // we need to calculate xy/(xy + z)
>             // where z = (1-x)(1-y)
> 
>             // firstly, calculate z and xy
>             double z = 0d;
>             double xy = 0d;
>             for (int i = 0; i < wps.length; i++)
> 			{
> 				// dss begin
> 				if ( wps[ i].getMatchingCount() 
> == 0) continue;
> 				if ( wps[ 
> i].getNonMatchingCount() == 0) continue;
> 				// dss end
>                                 ...
> 
> 
> 
> 
> 
> =====
> 
> 
> 
> 		
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