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classifier output as support function
Posted: 10 March 2010 02:12 PM   [ Ignore ]  
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Hello,
I am relatively new to prtools -learning in progress:)

I’m looking for a way to achieve from classifier (mapping) not direct class label but a support function value in case, for instance, neural nets - or probabilities that given object is of class X. Generally I want to achieve soft value from given classifier. Is it easly possible or requires a lot of coding?
Is it correct assumption that after operation dataset * mapping I should get a new dataset where
resulting nlab array should contain soft labels set by mapping?

Kind regards,
Tomasz Wilk

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Posted: 10 March 2010 03:06 PM   [ Ignore ]   [ # 1 ]  
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Some classifiers give by themselves normalised soft outputs, e.g.fisherc and svc.
Other one, the ones based on density estimation need a normalisation by classc, e.g.:

a = gendath; % dataset
[trainset,testset] = gendat(a,0.5); % split in datasets for training and testing
w = qdc(trainset); % classifier
d = testset*w*classc; % compute classification matrix
+d % show confidences (here identical to posterior probs)

For classifiers that don’t need normalisation, classc is redundant, but doesn’t change anything.

Bob Duin

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Posted: 11 March 2010 08:55 AM   [ Ignore ]   [ # 2 ]  
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Thank you, that is what I was looking for :)

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